query: the minimum number of carbon in a monosaccharide is

pos: Monosaccharide terminal carbon) is chiral, giving rise to a number of isomeric forms, all with the same chemical formula. For instance, galactose and glucose are both aldohexoses, but have different physical structures and chemical properties. With few exceptions (e.g., deoxyribose), monosaccharides have this chemical formula: (CHO), where conventionally "x" ≥ 3. Monosaccharides can be classified by the number "x" of carbon atoms they contain: triose (3), tetrose (4), pentose (5), hexose (6), heptose (7), and so on. The most important monosaccharide, glucose, is a hexose. Examples of heptoses include the ketoses, mannoheptulose and sedoheptulose. Monosaccharides with eight or more carbons are

pos: Monosaccharide nomenclature Monosaccharide nomenclature Monosaccharide nomenclature is a set of conventions used in chemistry to name the compounds known as monosaccharides or "simple sugars" — the basic structural units of carbohydrates, which cannot be hydrolysed into simpler units. The elementary formula of a simple monosaccharide is CHO, where the integer "n" is at least 3 and rarely greater than 7. Simple monosaccharides may be named generically according on the number of carbon atoms "n": trioses, tetroses, pentoses, hexoses, etc. Every simple monosaccharide has an acyclic (open chain) form, which can be written as H-(CH(OH))-(C=O)-(CH(OH))-H; that is, a straight chain of carbon atoms,

pos: Food chemistry instances is reduce the amount of water or alter the water's characteristics to enhance shelf-life. Such methods include dehydration, freezing, and refrigeration This field encompasses the" "physiochemical principles of the reactions and conversions that occur during the manufacture, handling, and storage of foods"". Comprising 75% of the biological world and 80% of all food intake for human consumption, the most common known human carbohydrate is Sucrose. The simplest version of a carbohydrate is a monosaccharide which contains carbon, hydrogen, and oxygen in a 1:2:1 ratio under a general formula of CHO where n is a minimum of 3. Glucose is

pos: Biochemistry which among other properties contains carbon, hydrogen, and oxygen, mostly in a ratio of 1:2:1 (generalized formula CHO, where "n" is at least 3). Glucose (CHO) is one of the most important carbohydrates; others include fructose (CHO), the sugar commonly associated with the sweet taste of fruits, and deoxyribose (CHO). A monosaccharide can switch between acyclic (open-chain) form and a cyclic form. The open-chain form can be turned into a ring of carbon atoms bridged by an oxygen atom created from the carbonyl group of one end and the hydroxyl group of another. The cyclic molecule has an hemiacetal or

pos: Pentose Pentose A pentose is a monosaccharide with five carbon atoms. Pentoses are organized into two groups: Aldopentoses have an aldehyde functional group at position 1. Ketopentoses have a ketone functional group at position 2 or 3. In the cell, pentoses have a higher metabolic stability than hexoses. The aldopentoses have three chiral centers; therefore, eight (2) different stereoisomers are possible. Ribose is a constituent of RNA, and the related molecule, deoxyribose, is a constituent of DNA. Phosphorylated pentoses are important products of the pentose phosphate pathway, most importantly ribose 5-phosphate (R5P), which is used in the synthesis of nucleotides and

pos: Monosaccharide nomenclature top in the diagram, skipping the keto group if any. These prefixes are attached to the systematic name of the molecular graph. So for example, -glucose is -"gluco"-hexose, -ribose is -"ribo"-pentose, and -psicose is -"ribo"-hexulose. Note that, in this nomenclature, mirror-image isomers differ only in the ''/'' prefix, even though all their hydroxyls are reversed. The following tables shows the Fischer projections of selected monosaccharides (in open-chain form), with their conventional names. The table shows all aldoses with 3 to 6 carbon atoms, and a few ketoses. For chiral molecules, only the '-' form (with the next-to-last hydroxyl on the

neg: Monosaccharide if the molecule contains a stereogenic center, specifically a carbon atom that is chiral (connected to four distinct molecular sub-structures). Those four bonds can have any of two configurations in space distinguished by their handedness. In a simple open-chain monosaccharide, every carbon is chiral except the first and the last atoms of the chain, and (in ketoses) the carbon with the keto group. For example, the triketose H(CHOH)(C=O)(CHOH)H (glycerone, dihydroxyacetone) has no stereogenic center, and therefore exists as a single stereoisomer. The other triose, the aldose H(C=O)(CHOH)H (glyceraldehyde), has one chiral carbon — the central one, number 2 — which

neg: -ose -ose The suffix -ose ( or ) is used in biochemistry to form the names of sugars. This Latin suffix means "full of", "abounding in", "given to", or "like". Numerous systems exist to name specific sugars more descriptively. Monosaccharides, the simplest sugars, may be named according to the number of carbon atoms in each molecule of the sugar: pentose is a five-carbon monosaccharide, and hexose is a six-carbon monosaccharide. Aldehyde monosaccharides may be called aldoses; ketone monosaccharides may be called ketoses. Larger sugars such as disaccharides and polysaccharides can be named to reflect their qualities. Lactose, a disaccharide found in

neg: Oligosaccharide nomenclature the Tollens’ reagent. The reducing and non-reducing ends of an oligosaccharide are conventionally drawn with the reducing-end monosaccharide residue furthest to the right and the non-reducing (or terminal) end furthest to the left. Naming of oligosaccharides proceeds from left to right (from the non-reducing end to the reducing end) as glycosyl [glycosyl] glycoses or glycosyl [glycosyl] glycosides, depending on whether or not the reducing end is a free hemiacetal group. In parentheses, between the names of the monosaccharide residues, the number of the anomeric carbon atom, an arrow symbol, and the number of the carbon atom bearing the connecting oxygen

neg: Monosaccharide is bonded to groups −H, −OH, −C(OH)H, and −(C=O)H. Therefore, it exists as two stereoisomers whose molecules are mirror images of each other (like a left and a right glove). Monosaccharides with four or more carbons may contain multiple chiral carbons, so they typically have more than two stereoisomers. The number of distinct stereoisomers with the same diagram is bounded by 2, where "c" is the total number of chiral carbons. The Fischer projection is a systematic way of drawing the skeletal formula of an acyclic monosaccharide so that the handedness of each chiral carbon is well specified. Each stereoisomer

neg: Carbohydrate its chiral handedness. If the carbonyl group is an aldehyde, the monosaccharide is an aldose; if the carbonyl group is a ketone, the monosaccharide is a ketose. Monosaccharides with three carbon atoms are called trioses, those with four are called tetroses, five are called pentoses, six are hexoses, and so on. These two systems of classification are often combined. For example, glucose is an aldohexose (a six-carbon aldehyde), ribose is an aldopentose (a five-carbon aldehyde), and fructose is a ketohexose (a six-carbon ketone). Each carbon atom bearing a hydroxyl group (-OH), with the exception of the first and last carbons,

neg: Cord factor production levels and in this way disrupts its cell wall assembly. A cord factor molecule is composed of a trehalose sugar, a disaccharide, that is esterified to two mycolic acid residues. One of the two mycolic acid residues is attached to the sixth carbon of one monosaccharide, while the other mycolic acid residue is attached to the sixth carbon of the other monosaccharide. Therefore, cord factor is also named trehalose-6,6'-dimycolate. The carbon chain of the mycolic acid residues vary in length depending on the species of bacteria it is found in, but the general range is 20 to 80 carbon

neg: Monosaccharide large number of biologically important modified monosaccharides exist: Monosaccharide Monosaccharides (from Greek "monos": single, "sacchar": sugar), also called simple sugars, are the simplest form of sugar and the most basic units of carbohydrates. They cannot be further hydrolyzed to simpler chemical compounds. The general formula is . They are usually colorless, water-soluble, and crystalline solids. Some monosaccharides have a sweet taste. Examples of monosaccharides include glucose (dextrose), fructose (levulose), and galactose. Monosaccharides are the building blocks of disaccharides (such as sucrose and lactose) and polysaccharides (such as cellulose and starch). Each carbon atom that supports a hydroxyl group (so, all

neg: Monosaccharide another ring formation. The stereochemical structure of a cyclic monosaccharide can be represented in a Haworth projection. In this diagram, the α-isomer for the pyranose form of a D-aldohexose has the -OH of the anomeric carbon below the plane of the carbon atoms, while the β-isomer has the -OH of the anomeric carbon above the plane. Pyranoses typically adopt a chair conformation, similar to that of cyclohexane. In this conformation, the α-isomer has the -OH of the anomeric carbon in an axial position, whereas the β-isomer has the OH- of the anomeric carbon in equatorial position (considering D-aldohexose sugars). A

neg: Monosaccharide nomenclature formula of an open-chain monosaccharide so that each stereoisomer is uniquely identified. Two isomers whose molecules are mirror-images of each other are identified by prefixes '-' or '-', according to the handedness of the chiral carbon atom that is farthest from the carbonyl. In the Fischer projection, that is the second carbon from the bottom; the prefix is '-' or '-' according to whether the hydroxyl on that carbon lies to the right or left of the backbone, respectively. If the molecular graph is symmetrical (H(CHOH)"x"(CO)(CHOH)"x"H) and the two halves are mirror images of each other, then the molecule is

neg: Monosaccharide rarely observed as they are quite unstable. In aqueous solutions monosaccharides exist as rings if they have more than four carbons. Simple monosaccharides have a linear and unbranched carbon skeleton with one carbonyl (C=O) functional group, and one hydroxyl (OH) group on each of the remaining carbon atoms. Therefore, the molecular structure of a simple monosaccharide can be written as H(CHOH)(C=O)(CHOH)H, where "n" + 1 + "m" = "x"; so that its elemental formula is CHO. By convention, the carbon atoms are numbered from 1 to "x" along the backbone, starting from the end that is closest to the C=O

neg: Carbohydrate three principal groups, namely sugars, oligosaccharides and polysaccharides DP * = Degree of polymerization Monosaccharides are the simplest carbohydrates in that they cannot be hydrolyzed to smaller carbohydrates. They are aldehydes or ketones with two or more hydroxyl groups. The general chemical formula of an unmodified monosaccharide is (C•HO), literally a "carbon hydrate". Monosaccharides are important fuel molecules as well as building blocks for nucleic acids. The smallest monosaccharides, for which n=3, are dihydroxyacetone and D- and L-glyceraldehydes. Monosaccharides are classified according to three different characteristics: the placement of its carbonyl group, the number of carbon atoms it contains, and

neg: Monosaccharide Otherwise, it receives the - prefix. In the Fischer projection, the - and - prefixes specifies the configuration at the carbon atom that is second from bottom: - if the hydroxyl is on the right side, and - if it is on the left side. Note that the - and - prefixes do not indicate the direction of rotation of polarized light, which is a combined effect of the arrangement at all chiral centers. However, the two enantiomers will always rotate the light in opposite directions, by the same amount. See also . A monosaccharide often switches from the acyclic

neg: Monosaccharide nomenclature one of which is a carbonyl group, all the others bearing a hydrogen -H and a hydroxyl -OH each, with one extra hydrogen at either end. The carbons of the chain are conventionally numbered from 1 to "n", starting from the end which is closest to the carbonyl. If the carbonyl is at the very beginning of the chain (carbon 1), the monosaccharide is said to be an aldose, otherwise it is a ketose. These names can be combined with the chain length prefix, as in aldohexose or ketopentose. Most ketoses found in nature have the carbonyl in position 2;

neg: Monosaccharide is the number of carbons. Every aldose will have 2 stereoisomers where "n" > 2 is the number of carbons. These are also referred to as epimers which have the different arrangement of −OH and −H groups at the asymmetric or chiral carbon atoms (this does not apply to those carbons having the carbonyl functional group). Like many chiral molecules, the two stereoisomers of glyceraldehyde will gradually rotate the polarization direction of linearly polarized light as it passes through it, even in solution. The two stereoisomers are identified with the prefixes - and -, according to the sense of rotation:

neg: Maltose because it consists of two glucose molecules. Glucose is a hexose: a monosaccharide containing six carbon atoms. The two glucose units are in the pyranose form and are joined by an O-glycosidic bond, with the first carbon (C) of the first glucose linked to the fourth carbon (C) of the second glucose, indicated as (1→4). The link is characterized as α because the glycosidic bond to the anomeric carbon (C) is in the opposite plane from the substituent in the same ring (C of the first glucose). If the glycosidic bond to the anomeric carbon (C) were in the same

neg: Ketose Ketose A ketose is a monosaccharide containing one ketone group per molecule. The simplest ketose is dihydroxyacetone, which has only three carbon atoms, and it is the only one with no optical activity. All monosaccharide ketoses are reducing sugars, because they can tautomerize into aldoses via an aldol intermediate, and the resulting aldehyde group can be oxidised, for example in the Tollens' test or Benedict's test. Ketoses that are bound into glycosides, for example in the case of the fructose moiety of sucrose, are nonreducing sugars. All ketoses listed here are 2-ketoses, in other words, the carbonyl group is on

neg: Monosaccharide "glucose" means a specific pair of mirror-image aldohexoses. In the Fischer projection, one of the two glucose isomers has the hydroxyl at left on C3, and at right on C4 and C5; while the other isomer has the reversed pattern. These specific monosaccharide names have conventional three-letter abbreviations, like "Glu" for glucose and "Thr" for threose. Generally, a monosaccharide with "n" asymmetrical carbons has 2 stereoisomers. The number of open chain stereoisomers for an aldose monosaccharide is larger by one than that of a ketose monosaccharide of the same length. Every ketose will have 2 stereoisomers where "n" > 2

neg: Monosaccharide Monosaccharide Monosaccharides (from Greek "monos": single, "sacchar": sugar), also called simple sugars, are the simplest form of sugar and the most basic units of carbohydrates. They cannot be further hydrolyzed to simpler chemical compounds. The general formula is . They are usually colorless, water-soluble, and crystalline solids. Some monosaccharides have a sweet taste. Examples of monosaccharides include glucose (dextrose), fructose (levulose), and galactose. Monosaccharides are the building blocks of disaccharides (such as sucrose and lactose) and polysaccharides (such as cellulose and starch). Each carbon atom that supports a hydroxyl group (so, all of the carbons except for the primary and

neg: Monosaccharide same name commonly is used for the open- and closed-chain isomers. Thus, for example, the term "glucose" may signify glucofuranose, glucopyranose, the open-chain form, or a mixture of the three. Cyclization creates a new stereogenic center at the carbonyl-bearing carbon. The −OH group that replaces the carbonyl's oxygen may end up in two distinct positions relative to the ring's midplane. Thus each open-chain monosaccharide yields two cyclic isomers (anomers), denoted by the prefixes α- and β-. The molecule can change between these two forms by a process called mutarotation, that consists in a reversal of the ring-forming reaction followed by

neg: Polysaccharide type, the polysaccharide is called a "homopolysaccharide" or "homoglycan", but when more than one type of monosaccharide is present they are called "heteropolysaccharides" or "heteroglycans". Natural saccharides are generally of simple carbohydrates called monosaccharides with general formula (CHO) where "n" is three or more. Examples of monosaccharides are glucose, fructose, and glyceraldehyde. Polysaccharides, meanwhile, have a general formula of C(HO) where "x" is usually a large number between 200 and 2500. When the repeating units in the polymer backbone are six-carbon monosaccharides, as is often the case, the general formula simplifies to (CHO), where typically 40≤n≤3000. As a rule of

neg: Aldose Aldose An aldose is a monosaccharide (a simple sugar) with a carbon backbone chain with a carbonyl group on the endmost carbon atom, making it an aldehyde, and hydroxyl groups connected to all the other carbon atoms. Aldoses can be distinguished from ketoses, which have the carbonyl group away from the end of the molecule, and are therefore ketones. Like most carbohydrates, simple aldoses have the general chemical formula C(HO). Because formaldehyde (n=1) and glycolaldehyde (n=2) are not generally considered to be carbohydrates, the simplest possible aldose is the triose glyceraldehyde, which only contains three carbon atoms. Because they have

neg: Glycal discovered his mistake, the name “glycal” was adopted as a general name for all sugars with a double bond between carbon atoms 1 and 2. Glycals can be formed as pyranose (six-membered) or furanose (five-membered) rings, depending on the monosaccharide used as a starting material to synthesize the glycal. Glycals can also be classified as "endo"-glycals or "exo"-glycals. A glycal is an endo-glycal when the double bond is within the ring. If the hydroxyl group on carbon 1 has been replaced with another carbon atom, a double bond can also form outside the ring between carbon 1 and this new

neg: Carbohydrate synthesis Carbohydrate synthesis Carbohydrate synthesis is a sub-field of organic chemistry concerned specifically with the generation of natural and unnatural carbohydrate structures. This can include the synthesis of monosaccharide residues or structures containing more than one monosaccharide, known as oligosaccharides. Generally speaking, carbohydrates can be classified into two groups, simple sugars and complex carbohydrates. Simple sugars, also called monosaccharides, are carbohydrates which can not be converted into smaller sugars by hydrolysis. When two or more monosaccharide units are connected to one another via a glycoside linkage, complex carbohydrates are formed. Complex carbohydrates, according to the different number of monosaccharide units, can

neg: N-Acetylmuramic acid N-Acetylmuramic acid "N"-Acetylmuramic acid, or MurNAc, is the ether of lactic acid and "N"-acetylglucosamine with a chemical formula of CHNO. It is part of a biopolymer in the bacterial cell wall, which is built from alternating units of "N"-acetylglucosamine (GlcNAc) and "N"-acetylmuramic acid (MurNAc), cross-linked with oligopeptides at the lactic acid residue of MurNAc. This layered structure is called peptidoglycan. MurNAc is a monosaccharide derivative of "N"-acetylglucosamine. "N"-Acetylmuramic acid (MurNAc) is part of the peptidoglycan polymer of bacterial cell walls. MurNAc is covalently linked to "N"-acetylglucosamine and may also be linked through the hydroxyl on carbon number 4 to the

neg: Aldose of which represent important stereochemical information about the forms they depict. Aldose An aldose is a monosaccharide (a simple sugar) with a carbon backbone chain with a carbonyl group on the endmost carbon atom, making it an aldehyde, and hydroxyl groups connected to all the other carbon atoms. Aldoses can be distinguished from ketoses, which have the carbonyl group away from the end of the molecule, and are therefore ketones. Like most carbohydrates, simple aldoses have the general chemical formula C(HO). Because formaldehyde (n=1) and glycolaldehyde (n=2) are not generally considered to be carbohydrates, the simplest possible aldose is the

neg: Atomic mass (nucleon count). The amount that the ratio of atomic masses to mass number deviates from 1 is as follows: the deviation starts positive at hydrogen-1, then decreases until it reaches a local minimum at helium-4. Isotopes of lithium, beryllium, and boron are less strongly bound than helium, as shown by their increasing mass-to-mass number ratios. At carbon, the ratio of mass (in daltons) to mass number is defined as 1, and after carbon it becomes less than one until a minimum is reached at iron-56 (with only slightly higher values for iron-58 and nickel-62), then increases to positive values in

neg: Carbohydrate or L is made according to the orientation of the asymmetric carbon furthest from the carbonyl group: in a standard Fischer projection if the hydroxyl group is on the right the molecule is a D sugar, otherwise it is an L sugar. The "D-" and "L-" prefixes should not be confused with "d-" or "l-", which indicate the direction that the sugar rotates plane polarized light. This usage of "d-" and "l-" is no longer followed in carbohydrate chemistry. The aldehyde or ketone group of a straight-chain monosaccharide will react reversibly with a hydroxyl group on a different carbon atom

neg: Mannoheptulose produced during photosynthesis the precise biological pathway for the synthesis of mannoheptulose was unknown as of 2002. Like other sugars it is transported in the phloem. Mannoheptulose Mannoheptulose is a heptose, a monosaccharide with seven carbon atoms, and a ketose, with the characteristic carbonyl group of the carbohydrate present on a secondary carbon (functioning as a ketone group). The sugar-alcohol form of mannoheptulose is known as perseitol. Mannoheptulose is a competitive and non-competitive inhibitor of both hexokinase and the related liver isozyme glucokinase. Because of its inhibition of glycolysis "in vitro", it has been investigated as a novel nutraceuticals for

neg: Monosaccharide nomenclature prefixes 'α-' and 'β-', which denote the relative configuration of the anomeric carbon to that of the stereocenter at the other end of the carbon chain. To determine if the sugar is α or β, the structure is drawn in a Fischer projection; if the endocyclic oxygen (O5) and exocyclic oxygen (O1) are "cis", the sugar is α; if they are "trans", the sugar is β. Examples Glycosides are saccharides in which the hydroxyl -OH at the anomeric centre is replaced by an oxygen-bridged group -OR. The carbohydrate part of the molecule is called glycone, the -O- bridge is the

neg: Mannoheptulose Mannoheptulose Mannoheptulose is a heptose, a monosaccharide with seven carbon atoms, and a ketose, with the characteristic carbonyl group of the carbohydrate present on a secondary carbon (functioning as a ketone group). The sugar-alcohol form of mannoheptulose is known as perseitol. Mannoheptulose is a competitive and non-competitive inhibitor of both hexokinase and the related liver isozyme glucokinase. Because of its inhibition of glycolysis "in vitro", it has been investigated as a novel nutraceuticals for weight management for dogs. However, while mannoheptulose is suggested to affect the energy balance of adult dogs, independent of dosage and physical activity, research disagrees whether

neg: Ribose itself is named as a partial rearrangement of letters in the word 'arabinose'. The ribose β-D-ribofuranose forms part of the backbone of RNA. It is related to deoxyribose, which is found in DNA. Phosphorylated derivatives of ribose such as ATP and NADH play central roles in metabolism. cAMP and cGMP, formed from ATP and GTP, serve as secondary messengers in some signalling pathways. Ribose is an aldopentose (a monosaccharide containing five carbon atoms) that, in its open chain form, has an aldehyde functional group at one end. In the conventional numbering scheme for monosaccharides, the carbon atoms are numbered from

neg: Hexose neighbouring hydroxyl functional groups to form intramolecular hemiacetals and hemiketals, respectively. The resulting ring structure is related to pyran, and is termed a pyranose. The ring spontaneously opens and closes, allowing rotation to occur about the bond between the carbonyl group and the neighbouring carbon atom, yielding two distinct configurations (α and β). This process is termed mutarotation. Hexose sugars can form dihexose sugars with a condensation reaction to form a 1,6-glycosidic bond. Hexose In bio-organic chemistry, a hexose is a monosaccharide with six carbon atoms, having the chemical formula CHO. Hexoses are classified by functional group, with aldohexoses having

neg: Ketose the second carbon atom from the end: Ketoses and aldoses can be chemically differentiated through Seliwanoff's test, where the sample is heated with acid and resorcinol. The test relies on the dehydration reaction which occurs more quickly in ketoses, so that while aldoses react slowly, producing a light pink color, ketoses react more quickly and strongly to produce a dark red color. Ketoses can isomerize to aldoses through the Lobry-de Bruyn-van Ekenstein transformation. Ketose A ketose is a monosaccharide containing one ketone group per molecule. The simplest ketose is dihydroxyacetone, which has only three carbon atoms, and it is the

neg: Monosaccharide the same carbon-oxygen ring (although they lack the double bonds of these two molecules). For example, the aldohexose glucose may form a hemiacetal linkage between the hydroxyl on carbon 1 and the oxygen on carbon 4, yielding a molecule with a 5-membered ring, called glucofuranose. The same reaction can take place between carbons 1 and 5 to form a molecule with a 6-membered ring, called glucopyranose. Cyclic forms with a 7-atom ring (the same of oxepane), rarely encountered, are called heptoses. For many monosaccharides (including glucose), the cyclic forms predominate, in the solid state and in solutions, and therefore the

neg: Glyceraldehyde 3-phosphate cycle to continue. G3P is generally considered the prime end-product of photosynthesis and it can be used as an immediate food nutrient, combined and rearranged to form monosaccharide sugars, such as glucose, which can be transported to other cells, or packaged for storage as insoluble polysaccharides such as starch. 6 CO + 6 RuBP (+ energy from 12 ATP and 12 NADPH) →12 G3P (3-carbon) 10 G3P (+ energy from 6 ATP) → 6 RuBP (i.e. starting material regenerated) 2 G3P → glucose (6-carbon). Glyceraldehyde 3-phosphate occurs as a byproduct in the biosynthesis pathway of tryptophan, an essential amino acid

neg: Saprotrophic nutrition such organisms must be able to provide carbon, proteins, vitamins and in some cases, ions. Due to the carbon composition of the majority of organisms, dead and organic matter provide rich sources of disaccharides and polysaccharides such as maltose and starch, and of the monosaccharide glucose. In terms of nitrogen-rich sources, saprotrophs require combined protein for the creation of proteins, which is facilitated by the absorption of amino acids, and usually taken from rich soil. Although both ions and vitamins are rare, thiamine or ions such as potassium, phosphorus, and magnesium aid the growth of the mycelium. Saprotrophic nutrition Saprotrophic

neg: Carbohydrate on each carbon atom that is not part of the aldehyde or ketone functional group. Examples of monosaccharides are glucose, fructose, and glyceraldehydes. However, some biological substances commonly called "monosaccharides" do not conform to this formula (e.g. uronic acids and deoxy-sugars such as fucose) and there are many chemicals that do conform to this formula but are not considered to be monosaccharides (e.g. formaldehyde CHO and inositol (CHO)). The open-chain form of a monosaccharide often coexists with a closed ring form where the aldehyde/ketone carbonyl group carbon (C=O) and hydroxyl group (–OH) react forming a hemiacetal with a new C–O–C

neg: Legume lectin are easy to obtain and purify. Over the years, a quite impressive amount of structural data has been gathered. Well-studied members of this protein family include phytohemagglutinin and concanavalin A. The legume lectins use an ingenious framework for binding specific sugars. This framework consists of a conserved monosaccharide binding site in which four conserved residues from four separate regions in the protein confer affinity (see figure), a variable loop that confers monosaccharide specificity and a number of subsites around the monosaccharide binding site that harbour additional sugar residues or hydrophobic groups. The legume lectins are also interesting from the point

neg: Alkane stereochemistry Alkane stereochemistry Alkane stereochemistry concerns the stereochemistry of alkanes. Alkane conformers are one of the subjects of alkane stereochemistry. Alkane conformers arise from rotation around sp hybridised carbon carbon sigma bonds. The smallest alkane with such a chemical bond, ethane, exists as an infinite number of conformations with respect to rotation around the C–C bond. Two of these are recognised as energy minimum (staggered conformation) and energy maximum (eclipsed conformation) forms. The existence of specific conformations is due to hindered rotation around sigma bonds, although a role for hyperconjugation is proposed by a competing theory. The importance of energy minimum

neg: Sporobolomyces koalae a range of ; growth stops at . Like other "Sporobolomyces" species, "S. koalae" has coenzyme Q as its major ubiquinone, it lacks the monosaccharide xylose in whole-cell hydrolysates, and it cannot ferment sugars. In carbon assimilation tests (used to assess the ability of the yeast to utilize different carbohydrates as its sole source of carbon aerobically), "S. koalae" was shown to be able to use glucose, sucrose, maltose, cellobiose, raffinose, soluble starch, D-mannitol, and succinic acid; it has a weak ability to use trehalose, melezitose, inulin, L-arabinose, glycerine, D-sorbitol, salicin, and D-gluconate. It can use ammonium sulphate and potassium

neg: Nuclear magnetic resonance spectroscopy of carbohydrates The typical ranges of specific carbohydrate carbon chemical shifts in the unsubstituted monosaccharides are: Direct carbon-proton coupling constants are used to study the anomeric configuration of a sugar. Vicinal proton-proton coupling constants are used to study stereo orientation of protons relatively to the other protons within a sugar ring, thus identifying a monosaccharide. Vicinal heteronuclear H-C-O-C coupling constants are used to study torsional angles along glycosidic bond between sugars or along exocyclic fragments, thus revealing a molecular conformation. Sugar rings are relatevely rigid molecular fragments, thus vicinal proton-proton couplings are characteristic: NOEs are sensitive to interatomic distances, allowing their usage

neg: Glucose Glucose Glucose (also called dextrose) is a simple sugar with the molecular formula . Glucose is the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using energy from sunlight. There it is used to make cellulose in cell walls, which is the most abundant carbohydrate. In energy metabolism, glucose is the most important source of energy in all organisms. Glucose for metabolism is partially stored as a polymer, in plants mainly as starch and amylopectin and in animals as glycogen. Glucose circulates in the blood

neg: Glycome i.e. [CHO]n. Monosaccharides are a carbohydrate that cannot be hydrolyzed into a simpler carbohydrate and are the building blocks of oligosaccharides and polysaccharides. Oligosaccharides are linear or branched chains of monosaccharides attached to one another via glycosidic linkages. The number of monosaccharide units can vary. Polysaccharides are glycans composed of repeating monosaccharides, generally greater than ten monosaccharide units in length. The glycome exceeds the complexity of the proteome as a result of the even greater diversity of the glycome's constituent carbohydrates and is further complicated by the sheer multiplicity of possibilities in the combination and interaction of the carbohydrates with

neg: Dithioerythritol are "trans" to each other, whereas they are "cis" to each other in DTE. Dithioerythritol Dithioerythritol (DTE) is a sulfur containing sugar derived from the corresponding 4-carbon monosaccharide erythrose. It is an epimer of dithiothreitol (DTT). The molecular formula for DTE is CHOS. Like DTT, DTE makes an excellent reducing agent, although its standard reduction potential is not quite as negative, i.e., DTE is slightly less effective at reducing than DTT. This is presumably because the orientation of the OH groups in its cyclic disulfide-bonded form (oxidized form) is less stable due to greater steric repulsion than their orientation in

neg: Arabinose Arabinose Arabinose is an aldopentose – a monosaccharide containing five carbon atoms, and including an aldehyde (CHO) functional group. For biosynthetic reasons, most saccharides are almost always more abundant in nature as the ""-form, or structurally analogous to -glyceraldehyde. However, -arabinose is in fact more common than -arabinose in nature and is found in nature as a component of biopolymers such as hemicellulose and pectin. The -arabinose operon, also known as the araBAD operon, has been the subject of much biomolecular research. The operon directs the catabolism of arabinose in "E. coli", and it is dynamically activated in the presence

neg: Xylose Xylose Xylose ("cf." , "xylon", "wood") is a sugar first isolated from wood, and named for it. Xylose is classified as a monosaccharide of the aldopentose type, which means that it contains five carbon atoms and includes an aldehyde functional group. It is derived from hemicellulose, one of the main constituents of biomass. Like most sugars, it can adopt several structures depending on conditions. With its free aldehyde group, it is a reducing sugar. The acyclic form of xylose has chemical formula HOCH(CH(OH))CHO. The cyclic hemiacetal isomers are more prevalent in solution and are of two types: the pyranoses, which

neg: Threose centers, where "the prefixes... designate the relative configuration of the centers". As is depicted in a Fischer projection of -threose, the adjacent substituents will have a syn orientation in the isomer referred to as "threo", and are anti in the isomer referred to as "erythro". Threose Threose is a four-carbon monosaccharide with molecular formula CHO. It has a terminal aldehyde group rather than a ketone in its linear chain, and so is considered part of the aldose family of monosaccharides. The threose name can be used to refer to both the - and -stereoisomers, and more generally to the racemic

neg: Arabinose diabetic patients. These foods are especially popular in Japan and China, where arabinose is legally used as a food additive. Arabinose is a potential prebiotic, because it cannot be absorbed by human intestine and could be utilized by probiotics such as bifidobacteria. This claim requires further validation. Arabinose Arabinose is an aldopentose – a monosaccharide containing five carbon atoms, and including an aldehyde (CHO) functional group. For biosynthetic reasons, most saccharides are almost always more abundant in nature as the ""-form, or structurally analogous to -glyceraldehyde. However, -arabinose is in fact more common than -arabinose in nature and is found

neg: Ectomycorrhiza defense response suppression by the EcM fungi, though details concerning its nature and mechanisms have yet to be determined. This is well illustrated by the monosaccharide uptake system in "Amanita muscaria". Carbon uptake requires a transporter, AmMST1, that is only expressed when the fungus is cultured at low glucose levels in multiple mycorrhizal associations. This expression, and increased import of monosaccharides by the fungus, is met with an increase in the supply of photoassimilates from the plant host. In the reverse direction, phosphoenolpyruvate carboxylase (PEPC) moderates the assimilation of ammonium and the transport of amino acids from fungus to plant.

neg: Root mucilage amino acids, which are the building blocks of life. This collective secretion is known as root exudate. This root exudate prevents root infection from bacteria and fungi, helps the roots to penetrate through the soil, and can create a micro-climate that is beneficial to the plant. To determine the sugars within root mucilage, monosaccharide analysis and monosaccharide linkage analysis are undertaken. Monosaccharide linkage analysis involves methylating the root mucilage, which contains polysaccharides. The root mucilage is hydrolysed using acid to break down the polysaccharides into their monosaccharide components. The subsistent monosaccharides are then reduced to open their rings. The open

neg: Ketohexose carbon.Though all of these share similar structures, each have their own use and properties. Fructose in both L and D configurations is soluble in water, alcohol and ether. D-Sorbose is commonly used in the commercial synthesis of ascorbic acid. D-Tagatose is a rare natural ketohexose that is found in small quantities in food and has various health benefits. Ketohexose A ketohexose is a ketone-containing hexose (a six-carbon monosaccharide). The most common ketohexoses, each of which represents a pair of enantiomers (- and -isomers), include psicose, fructose, sorbose, and tagatose. Ketohexose is stable over a wide pH range, and with a

neg: Glucose be quantified. Glucose uptake in cells of organisms is measured with 2-deoxy-D-glucose or fluorodeoxyglucose. (F)fluorodeoxyglucose is used as a tracer in positron emission tomography in oncology and neurology, where it is by far the most commonly used diagnostic agent. Glucose Glucose (also called dextrose) is a simple sugar with the molecular formula . Glucose is the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using energy from sunlight. There it is used to make cellulose in cell walls, which is the most abundant carbohydrate. In

neg: Carbohydrate storage of energy (e.g. starch and glycogen) and as structural components (e.g. cellulose in plants and chitin in arthropods). The 5-carbon monosaccharide ribose is an important component of coenzymes (e.g. ATP, FAD and NAD) and the backbone of the genetic molecule known as RNA. The related deoxyribose is a component of DNA. Saccharides and their derivatives include many other important biomolecules that play key roles in the immune system, fertilization, preventing pathogenesis, blood clotting, and development. Starch and sugars are the most important carbohydrates in human diet. They are found in a wide variety of natural and processed foods. Starch

neg: Hexose Hexose In bio-organic chemistry, a hexose is a monosaccharide with six carbon atoms, having the chemical formula CHO. Hexoses are classified by functional group, with aldohexoses having an aldehyde at position 1, and ketohexoses having a ketone at position 2. The aldohexoses have four chiral centres for a total of 16 possible aldohexose stereoisomers (2). The / configuration is based on the orientation of the hydroxyl at position 5, and does not refer to the direction of optical activity. The eight -aldohexoses are: Of these -isomers, all except -altrose are naturally occurring. -Altrose, however, has been isolated from strains of

neg: Carbohydrate for the formation, breakdown and interconversion of carbohydrates in living organisms. The most important carbohydrate is glucose, a simple sugar (monosaccharide) that is metabolized by nearly all known organisms. Glucose and other carbohydrates are part of a wide variety of metabolic pathways across species: plants synthesize carbohydrates from carbon dioxide and water by photosynthesis storing the absorbed energy internally, often in the form of starch or lipids. Plant components are consumed by animals and fungi, and used as fuel for cellular respiration. Oxidation of one gram of carbohydrate yields approximately 9 kJ (4 kcal) of energy, while the oxidation of

neg: Threose Threose Threose is a four-carbon monosaccharide with molecular formula CHO. It has a terminal aldehyde group rather than a ketone in its linear chain, and so is considered part of the aldose family of monosaccharides. The threose name can be used to refer to both the - and -stereoisomers, and more generally to the racemic mixture (/-, equal parts - and -) as well as to the more generic threose structure (absolute stereochemistry unspecified). The prefix "threo" which derives from threose (and "erythro" from a corresponding diastereomer erythrose) offer a useful way to describe general organic structures with adjacent chiral

neg: Glycolaldehyde four species, which rapidly interconvert. It is the only possible diose, a 2-carbon monosaccharide, although a diose is not strictly a saccharide. While not a true sugar, it is the simplest sugar-related molecule. It is reported to taste sweet. Glycolaldehyde is the second most abundant compound formed when preparing pyrolysis oil (up to 10% by weight). Glycolaldehyde can be synthesized by the oxidation of ethylene glycol using hydrogen peroxide in the presence of Iron (II) sulphate. It can form by action of ketolase on fructose 1,6-bisphosphate in an alternate glycolysis pathway. This compound is transferred by thiamine pyrophosphate during the

neg: Reducing sugar sugars like fructose are considered reducing sugars but it is the isomer containing an aldehyde group which is reducing since ketones cannot be oxidized without decomposition of the sugar. This type of isomerization is catalyzed by the base present in solutions which test for the presence of aldehydes. Aldoses or aldehyde-bearing sugars are reducing also because during oxidation of aldoses, there are certain oxidizing agents that are reduced. The "reducing end" of a disaccharide is the monosaccharide with a free anomeric carbon that is not involved in a glycosidic bond and is thus capable of converting to the open-chain form.

neg: Ribose Ribose Ribose is a carbohydrate with the formula CHO; specifically, it is a pentose monosaccharide (simple sugar) with linear form H−(C=O)−(CHOH)−H, which has all the hydroxyl groups on the same side in the Fischer projection. The term may refer to either of two enantiomers. The term usually indicates -ribose, which occurs widely in nature and is discussed here. Its synthetic mirror image, -ribose, is not found in nature. -Ribose was first reported in 1891 by Emil Fischer. It is a C'-2 carbon epimer of the sugar -arabinose (both isomers of which are named for their source, gum arabic) and ribose

neg: Dithioerythritol Dithioerythritol Dithioerythritol (DTE) is a sulfur containing sugar derived from the corresponding 4-carbon monosaccharide erythrose. It is an epimer of dithiothreitol (DTT). The molecular formula for DTE is CHOS. Like DTT, DTE makes an excellent reducing agent, although its standard reduction potential is not quite as negative, i.e., DTE is slightly less effective at reducing than DTT. This is presumably because the orientation of the OH groups in its cyclic disulfide-bonded form (oxidized form) is less stable due to greater steric repulsion than their orientation in the disulfide-bonded form of DTT. In the disulfide-bonded form of DTT, these hydroxyl groups

neg: Glycal carbon. In this case, the product is called an "exo"-glycal. The glycal conformation that has been studied in most depth is that of the pyranose "endo"-glycal. The favoured conformation of this glycal is the half-chair, a result which has been confirmed by quantum mechanical calculations. The original Fischer glycal synthesis was the reductive elimination with zinc of a glycosyl halide. This glycosyl halide was formed from a monosaccharide starting material. Some other synthetic routes include: A general example of each synthetic route is given below (drawn with first discussed synthesis bottom right, moving clockwise): The double bond of a glycal

neg: Sialic acid virus variety. This diversity is an important fact that determines which species can be infected. When a certain influenza A virus is recognized by a sialic acid receptor the cell tends to endocytose the virus so the cell become infected. Sialic acid Sialic acid is a generic term for the "N"- or "O"-substituted derivatives of neuraminic acid, a monosaccharide with a nine-carbon backbone. It is also the name for the most common member of this group, N-acetylneuraminic acid (Neu5Ac or NANA). Sialic acids are found widely distributed in animal tissues and to a lesser extent in other organisms, ranging from

neg: Ketohexose Ketohexose A ketohexose is a ketone-containing hexose (a six-carbon monosaccharide). The most common ketohexoses, each of which represents a pair of enantiomers (- and -isomers), include psicose, fructose, sorbose, and tagatose. Ketohexose is stable over a wide pH range, and with a primary p"K" of 10.28, will only deprotonate at high pH, so is marginally less stable than aldohexose in solution. The basic formula for all ketohexoses is seen as <chem>C6H12O6</chem> with a molecular weight of 180.156 g/mol. The different variations of this type of molecule come from the varying R and S chirality around the third, fourth and fifth

neg: Glucose forms of glucose are colorless and easily soluble in water, acetic acid, and several other solvents. They are only sparingly soluble in methanol and ethanol. Glucose is a monosaccharide with formula CHO or H-(C=O)-(CHOH)-H, whose five hydroxyl (OH) groups are arranged in a specific way along its six-carbon back. Glucose is usually present in solid form as a monohydrate with a closed pyran ring (dextrose hydrate). In aqueous solution, on the other hand, it is has an open-chain to a small extent and is present predominantly as α- or β-pyranose, which partially mutually merge by mutarotation. From aqueous solutions, the

neg: Glucose that its hydroxy groups (with the exception of the hydroxy group on the anomeric carbon of -glucose) are in the equatorial position. Presumably, glucose is the most abundant natural monosaccharide because it is less glycated with proteins than other monosaccharides. Another hypothesis is that glucose, being the only D-aldohexose that has all five hydroxy substituents in the equatorial position in the form of β-D-glucose, is more readily accessible to chemical reactions, for example, for esterification or acetal formation. For this reason, D-glucose is also a highly preferred building block in natural polysaccharides (glycans). Polysaccharides that are composed solely of Glucose

neg: Monosaccharide -glyceraldehyde is dextrorotatory (rotates the polarization axis clockwise), while -glyceraldehyde is levorotatory (rotates it counterclockwise). The - and - prefixes are also used with other monosaccharides, to distinguish two particular stereoisomers that are mirror-images of each other. For this purpose, one considers the chiral carbon that is furthest removed from the C=O group. Its four bonds must connect to −H, −OH, −C(OH)H, and the rest of the molecule. If the molecule can be rotated in space so that the directions of those four groups match those of the analog groups in -glyceraldehyde's C2, then the isomer receives the - prefix.

neg: Xylose metabolism Xylose metabolism D-Xylose is a five-carbon aldose (pentose, monosaccharide) that can be catabolized or metabolized into useful products by a variety of organisms. There are at least four different pathways for the catabolism of D-xylose: An oxido-reductase pathway is present in eukaryotic microorganisms. Prokaryotes typically use an isomerase pathway, and two oxidative pathways, called Weimberg and Dahms pathways respectively, are also present in prokaryotic microorganisms. This pathway is also called the “Xylose Reductase-Xylitol Dehydrogenase” or XR-XDH pathway. Xylose reductase (XR) and xylitol dehydrogenase (XDH) are the first two enzymes in this pathway. XR is reducing D-xylose to xylitol using NADH

neg: Sialic acid Sialic acid Sialic acid is a generic term for the "N"- or "O"-substituted derivatives of neuraminic acid, a monosaccharide with a nine-carbon backbone. It is also the name for the most common member of this group, N-acetylneuraminic acid (Neu5Ac or NANA). Sialic acids are found widely distributed in animal tissues and to a lesser extent in other organisms, ranging from fungi to yeasts and bacteria, mostly in glycoproteins and gangliosides (they occur at the end of sugar chains connected to the surfaces of cells and soluble proteins). That is because it seems to have appeared late in evolution. However, it

neg: Xanthan lyase Xanthan lyase In enzymology, a xanthan lyase () is an enzyme that catalyzes the chemical reaction of cleaving the beta-D-mannosyl-beta-D-1,4-glucuronosyl bond on the polysaccharide xanthan. This enzyme belongs to the family of lyases, specifically those carbon-oxygen lyases acting on polysaccharides. Xanthan lyase was first identified and partially purified in 1987. Xanthan is a polysaccharide secreted by several different bacterial taxa, such as the plant pathogen "Xanthomonas campestris", and it consists of a main linear chain based on cellulose with side chains attached to alternate glucosyl (glucose) residues. These side chains contain three monosaccharide residues. Xanthan lyase is produced by bacteria

neg: Monosaccharide (open-chain) form to a cyclic form, through a nucleophilic addition reaction between the carbonyl group and one of the hydroxyls of the same molecule. The reaction creates a ring of carbon atoms closed by one bridging oxygen atom. The resulting molecule has an hemiacetal or hemiketal group, depending on whether the linear form was an aldose or a ketose. The reaction is easily reversed, yielding the original open-chain form. In these cyclic forms, the ring usually has 5 or 6 atoms. These forms are called furanoses and pyranoses, respectively — by analogy with furan and pyran, the simplest compounds with

neg: Monosaccharide nomenclature right side) is shown; the corresponding forms have mirror-image structures. Some of these monosaccharides are only synthetically prepared in the laboratory and not found in nature. For monosaccharides in their cyclic form, an infix is placed before the '-ose', '-ulose', or "'n"-ulose' suffix to specify the ring size. The infix is "furan" for a 5-atom ring, "pyran" for 6, "septan" for 7, and so on. Ring closure creates another chiral center at the anomeric carbon (the one with the hemiacetal or acetal functionality), and therefore each open-chain stereoisomer gives rise to two distinct stereoisomers (anomers). These are identified by the

neg: Xylose metabolism strain that efficiently produces ethanol. However, the effectiveness of D-xylose metabolizing laboratory strains do not always reflect their metabolism abilities on raw xylose products in nature. Since D-xylose is mostly isolated from agricultural residues such as wood stocks then the native or genetically altered yeasts will need to be effective at metabolizing these less pure natural sources. Varying expression of the XR and XDH enzyme levels have been tested in the laboratory in the attempt to optimize the efficiency of the D-xylose metabolism pathway. Xylose metabolism D-Xylose is a five-carbon aldose (pentose, monosaccharide) that can be catabolized or metabolized into

neg: Deoxyribose the Fischer projection. The term "2-deoxyribose" may refer to either of two enantiomers: the biologically important -2-deoxyribose and to the rarely encountered mirror image -2-deoxyribose. -2-deoxyribose is a precursor to the nucleic acid DNA. 2-deoxyribose is an aldopentose, that is, a monosaccharide with five carbon atoms and having an aldehyde functional group. In aqueous solution, deoxyribose primarily exists as a mixture of three structures: the linear form H−(C=O)−(CH)−(CHOH)−H and two ring forms, deoxyribofuranose ("C3′-endo"), with a five-membered ring, and deoxyribopyranose ("C2′-endo"), with a six-membered ring. The latter form is predominant (whereas the C3′-endo form is favored for ribose). As a

neg: N-Acetylmuramic acid carbon of L-alanine. A pentapeptide composed of L-alanyl-D-isoglutaminyl-L-lysyl-D-alanyl-D-alanine is added to the MurNAc in the process of making the peptidoglycan strands of the cell wall. Synthesis is inhibited by fosfomycin. N-Acetylmuramic acid "N"-Acetylmuramic acid, or MurNAc, is the ether of lactic acid and "N"-acetylglucosamine with a chemical formula of CHNO. It is part of a biopolymer in the bacterial cell wall, which is built from alternating units of "N"-acetylglucosamine (GlcNAc) and "N"-acetylmuramic acid (MurNAc), cross-linked with oligopeptides at the lactic acid residue of MurNAc. This layered structure is called peptidoglycan. MurNAc is a monosaccharide derivative of "N"-acetylglucosamine. "N"-Acetylmuramic acid (MurNAc)

neg: Keratan sulfate cell-surface or extracellular matrix proteins, termed core proteins. KS core proteins include lumican, keratocan, mimecan, fibromodulin, PRELP, osteoadherin, and aggrecan. The basic repeating disaccharide unit within keratan sulfate is -3Galβ1-4GlcNAcβ1-. This can be sulfated at carbon position 6 (C6) of either or both the Gal or GlcNAc monosaccharides. However, the detailed primary structure of specific KS types are best considered to be composed of three regions: The monosaccharide mannose is found within the linkage region of keratan sulfate type I (KSI). Disaccharides within the repeating region of KSII may be fucosylated and N-Acetylneuraminic acid caps the end of all keratan

neg: Oligosaccharide nomenclature or more monosaccharide residues. Polysaccharides have been given trivial names that reflect their origin. Two common examples are cellulose, a main component of the cell wall in plants, and starch, a name derived from the Anglo-Saxon stercan, meaning to stiffen. To name a polysaccharide composed of a single type of monosaccharide, that is a homopolysaccharide, the ending “-ose” of the monosaccharide is replaced with “-an”. For example, a glucose polymer is named glucan, a mannose polymer is named mannan, and a galactose polymer is named galactan. When the glycosidic linkages and configurations of the monosaccharides are known, they may be

neg: Sungnyung to a monosaccharide. This monosaccharide promotes digestion. Sungnyung contains a lot of monosaccharide called dextrin, which helps digestion. The ethanol extract of Sungnyung has a strong antioxidant effect and neutralizes the acidic constitution to alkalinity. Gabana which is a lot of ingredients in embryo bud of rice stabilizes the nerves and promotes fat breakdown. And it is also effective on diet. Sungnyung Sungnyung is a traditional Korean infusion made from boiled scorched rice. This drink is typically made from "nurungji", the roasted (but not charred) crust of rice that forms on the bottom of a pot after cooking rice. Water

neg: Neuraminic acid viruses have a neuraminidase enzyme, signified in the name "H#N#", where the H refers to an isoform of hemagglutinin and N refers to an isoform of viral neuraminidase. Neuraminic acid Neuraminic acid (5-amino-3,5-dideoxy--"glycero"--"galacto"-non-2-ulosonic acid) is a 9-carbon monosaccharide (a nonose), a derivative of a ketononose. Neuraminic acid may be visualized as the product of an aldol-condensation product of pyruvic acid and -mannosamine (2-amino-2-deoxy-mannose). Neuraminic acid does not occur naturally, but many of its derivatives are found widely distributed in animal tissues and in bacteria, especially in glycoproteins and gangliosides. The "N"- or "O"-substituted derivatives of neuraminic acid are collectively known

neg: Neuraminic acid Neuraminic acid Neuraminic acid (5-amino-3,5-dideoxy--"glycero"--"galacto"-non-2-ulosonic acid) is a 9-carbon monosaccharide (a nonose), a derivative of a ketononose. Neuraminic acid may be visualized as the product of an aldol-condensation product of pyruvic acid and -mannosamine (2-amino-2-deoxy-mannose). Neuraminic acid does not occur naturally, but many of its derivatives are found widely distributed in animal tissues and in bacteria, especially in glycoproteins and gangliosides. The "N"- or "O"-substituted derivatives of neuraminic acid are collectively known as sialic acids, the predominant form in mammalian cells being "N"-acetylneuraminic acid. The amino group bears either an acetyl or a glycolyl group. The hydroxyl substituents may vary

neg: Oligosaccharide nomenclature Oligosaccharide nomenclature Oligosaccharides and polysaccharides are an important class of polymeric carbohydrates found in virtually all living entities. Their structural features make their nomenclature challenging and their roles in living systems make their nomenclature important. Oligosaccharides are carbohydrates that are composed of several monosaccharide residues joined through glycosidic linkage, which can be hydrolyzed by enzymes or acid to give the constituent monosaccharide units. While a strict definition of an oligosaccharide is not established, it is generally agreed that a carbohydrate consisting of two to ten monosaccharide residues with a defined structure is an oligosaccharide. Some oligosaccharides, for example maltose, sucrose,

neg: Glucose amounts. The terms "glucose" and "-glucose" are generally used for these cyclic forms as well. The ring arises from the open-chain form by an intramolecular nucleophilic addition reaction between the aldehyde group (at C-1) and either the C-4 or C-5 hydroxyl group, forming a hemiacetal linkage, -C(OH)H-O-. The reaction between C-1 and C-5 yields a six-membered heterocyclic system called a pyranose, which is a monosaccharide sugar (hence "–ose") containing a derivatised pyran skeleton. The (much rarer) reaction between C-1 and C-4 yields a five-membered furanose ring, named after the cyclic ether furan. In either case, each carbon in the ring

neg: Isotopically pure diamond Isotopically pure diamond An isotopical pure diamond is a type of diamond that is composed entirely of one isotope of carbon. Isotopically pure diamonds have been manufactured from either the more common carbon isotope with mass number 12 (abbreviated as C) or the less common C isotope. Compared to natural diamonds that are composed of a mixture of C and C isotopes, isotopically pure diamonds possess improved characteristics such as increased thermal conductivity. Thermal conductivity of diamonds is at a minimum when C and C are in a ratio of 1:1 and reaches a maximum when the composition is 100%

neg: Threonine glycine levels. Threonine was the last of the 20 common proteinogenic amino acids to be discovered. It was discovered in 1936 by William Cumming Rose, collaborating with Curtis Meyer. The amino acid was named threonine because it was similar in structure to threonic acid, a four-carbon monosaccharide with molecular formula CHO Threonine is one of two proteinogenic amino acids with two chiral centers, the other being isoleucine. Threonine can exist in four possible stereoisomers with the following configurations: (2"S",3"R"), (2"R",3"S"), (2"S",3"S") and (2"R",3"R"). However, the name -threonine is used for one single diastereomer, (2"S",3"R")-2-amino-3-hydroxybutanoic acid. The second stereoisomer (2"S",3"S"), which

neg: Oligosaccharide nomenclature will help illustrate this concept: ((1→2)-α--galacto)-(1→4)-β--Glucan Oligosaccharide nomenclature Oligosaccharides and polysaccharides are an important class of polymeric carbohydrates found in virtually all living entities. Their structural features make their nomenclature challenging and their roles in living systems make their nomenclature important. Oligosaccharides are carbohydrates that are composed of several monosaccharide residues joined through glycosidic linkage, which can be hydrolyzed by enzymes or acid to give the constituent monosaccharide units. While a strict definition of an oligosaccharide is not established, it is generally agreed that a carbohydrate consisting of two to ten monosaccharide residues with a defined structure is an oligosaccharide.

neg: SS Virginis SS Virginis SS Virginis is a Mira variable star that appears with a strong red hue. It varies in magnitude from a minimum of 9.5 to a maximum of 7.4 over a period of 361 days. It is also considered to be a semiregular variable star, as its minimum and maximum magnitude are themselves variable over a period of decades. Its spectral class is C6e. Because it is so rich in carbon, SS Virginis is classified as a carbon star, along with stars like T Geminorum. SS Virginis, like all carbon Mira variables, has a hydrogen-alpha emission line that varies

neg: Glycal allows many other functional groups to be introduced into a monosaccharide. Like an alkene, a glycal can undergo electrophilic addition across the double bond to add in these new atoms such as halogens, epoxides, and nitrogen. The glycal double bond also allows a deoxy position (carbon in the ring that doesn’t have an oxygen bonded to it) to be easily introduced. Glycals have many uses in synthetic carbohydrate chemistry. They are commonly used as glycosylation donors, meaning that they can react with other monosaccharides to form a longer chain of monosaccharides called an oligosaccharide. Glycals can also have interesting applications

neg: Carbohydrate of monosaccharide catabolism: glycolysis and the citric acid cycle. In glycolysis, oligo- and polysaccharides are cleaved first to smaller monosaccharides by enzymes called glycoside hydrolases. The monosaccharide units can then enter into monosaccharide catabolism. A 2 ATP investment is required in the early steps of glycolysis to phosphorylate Glucose to Glucose 6-Phosphate (G6P) and Fructose 6-Phosphate (F6P) to Fructose 1,6-biphosphate (FBP), thereby pushing the reaction forward irreversibly. In some cases, as with humans, not all carbohydrate types are usable as the digestive and metabolic enzymes necessary are not present. Carbohydrate chemistry is a large and economically important branch of organic

neg: Oligosaccharide nomenclature included as a prefix to the name, with the notation for glycosidic linkages preceding the symbols designating the configuration. The following example will help illustrate this concept: (1→4)-β--Glucan A heteropolysaccharide is a polymer containing more than one kind of monosaccharide residue. The parent chain contains only one type of monosaccharide and should be listed last with the ending “-an”, and the other types of monosaccharides listed in alphabetical order as “glyco-” prefixes. When there is no parent chain, all different monosaccharide residues are to be listed alphabetically as “glyco-” prefixes and the name should end with “-glycan”. The following example

neg: Oligosaccharide nomenclature of the next monosaccharide unit are listed. Appropriate symbols are used to indicate the stereochemistry of the glycosidic bonds (α or β), the configuration of the monosaccharide residue ( or), and the substitutions at oxygen atoms ("O"). Maltose and a derivative of sucrose illustrate these concepts: Maltose: α--Glucopyranosyl-(1→4)-β--glucopyranose Methyl 2,3,4-tri-"O"-benzyl-6-deoxy-6-fluoro-α--galactopyranosyl-(1→4)-2,3,6-tri-"O"-acetyl-β--glucopyranoside In the case of branched oligosaccharides, meaning that the structure contains at least one monosaccharide residue linked to more than two other monosaccharide residues, terms designating the branches should be listed in square brackets, with the longest linear chain (the parent chain) written without square brackets. The following example will

neg: Alkane stereochemistry 1,3 positions. Evidence for the helix structure in the crystalline state is derived from X-ray crystallography and from NMR spectroscopy and circular dichroism in solution. Alkane stereochemistry Alkane stereochemistry concerns the stereochemistry of alkanes. Alkane conformers are one of the subjects of alkane stereochemistry. Alkane conformers arise from rotation around sp hybridised carbon carbon sigma bonds. The smallest alkane with such a chemical bond, ethane, exists as an infinite number of conformations with respect to rotation around the C–C bond. Two of these are recognised as energy minimum (staggered conformation) and energy maximum (eclipsed conformation) forms. The existence of specific

neg: Maunder Minimum lower geomagnetic latitudes. Because geomagnetic latitude is an important factor in auroral occurrence, (lower-latitude aurorae requiring higher levels of solar-terrestrial activity) it becomes important to allow for population migration and other factors that may have influenced the number of reliable auroral observers at a given magnetic latitude for the earlier dates. Decadal-scale cycles during the Maunder minimum can also be seen in the abundances of the beryllium-10 cosmogenic isotope (which unlike carbon-14 can be studied with annual resolution) but these appear to be in antiphase with any remnant sunspot activity. An explanation in terms of solar cycles in loss of

neg: Spörer Minimum is only reliable for periods after records of sunspot observations were routinely made by western astronomers. For periods before sunspot records, solar activity can be found from proxy methods, most notably the production of radioisotopes in the Earth's atmosphere from interaction with cosmic rays, which are modulated by the solar activity. The Carbon-14 method used by Spörer to identify the minimum makes use of the fact that high solar activity is correlated with low production of carbon-14 in the atmosphere. Wilfried Schröder published a table of observed aurora borealis during the Spörer Minimum which showed that the solar cycle was

neg: Dissolved organic carbon way from the North Atlantic and reaches a minimum in the North Pacific. Dissolved organic carbon is also extremely important in the transport of metals in aquatic systems. Metals form extremely strong complexes with dissolved organic carbon, enhancing metal solubility while also reducing metal bioavailability. Dissolved organic carbon Dissolved organic carbon (DOC), sometimes referred to as dissolved organic matter (DOM), is the fraction of total organic carbon that can pass through a filter, which typically ranges in size from 0.22 and 0.7 micrometers. Dissolved organic carbon is abundant in marine and freshwater systems and is one of the greatest cycled

neg: Maunder Minimum subsequent years. The drop in global average temperatures in paleoclimate reconstructions at the start of the Little Ice Age was between about 1560 and 1600, whereas the Maunder minimum began almost 50 years later. Past solar activity may be recorded by various proxies, including carbon-14 and beryllium-10. These indicate lower solar activity during the Maunder Minimum. The scale of changes resulting in the production of carbon-14 in one cycle is small (about one percent of medium abundance) and can be taken into account when radiocarbon dating is used to determine the age of archaeological artifacts. The interpretation of the beryllium-10