Monosaccharides ribose

The quantitative determinations of the monosaccharides ribose and deoxyribose are given in Protocols 1.2.2 and 1.2.3, respectively. The following protocol is useful for all monosaccharides. 

Carbohydrates are important for all plant and animal life. Polysaccharides serve for the storage of energy (e.g., starch and glycogen) and as struetural components (e g., cellulose in plants and ehitin in arthropods). The five-earbon monosaccharide, ribose, is an important component of coenzymes (e.g., ATP, FAD, and NAD) and RNA (see Chapter 2). 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, pathogenesis prevention, blood clotting, and development. Carbohydrates are present in dietary staples, such as breads, potatoes, noodles, and rice (Figure 5.1). 

Phosphate esters of glucose, fructose, and other monosaccharides are important metabolic intermediates, and the ribose moiety of nucleotides such as ATP and GTP is phosphorylated at the 5 -position (Figure 7.13). 

Monosaccharides, which cannot be broken down chemically to simpler carbohydrates. The most familiar monosaccharides contain either six carbon atoms per molecule (glucose, fructose, galactose,.. . ) or five (ribose, arabinose,.. . ). 

Die Reduktion der y-Lactone von On-sauren verschiedener Monosaccharide zu den entsprechenden Monosacchariden wird in einer geteilten Zelle an einer Quecksilber-Kathode undBlei- bzw. Platin-Anode in schwach saurem, waBrigen Milieu (Borat-Puffer) ausgefiihrt. Auf diese Weise sind d-Arabinose, n-Mannose, d-Talose, d-Ribose u. a. mit guter Ausbeute zuganglich1-4. 

Reactions of monosaccharides (for example, D-ribose, D-xylose, D-man-nose) with cyclohexene and tetracyanoethylene in liquid HF have been studied. 

The monosaccharides include glucose, the blood sugar and ribose, an important constiment of nucleotides and nucleic acids. 

Monosaccharides have the formula (CH2 0) , where n is between 3 and 6. Of the 70 or so monosaccharides that are known, 20 occur in nature. The most important naturally occurring monosaccharides contain five carbons (pentoses) or six carbons (hexoses). Structures of ribose, an important pentose, and a-glucose, a hexose that is the most common monosaccharide, are shown in Figure 13-14. As shown in the figure, it is customary to number the carbon atoms in a monosaccharide, beginning with the HCOH group adjacent to the ether linkage. 

Ribose and a-glucose are monosaccharides that occur in nature. The carbon atoms are numbered for identification purposes. 

Carbohydrates are classified based upon the products formed when they are hydrolyzed. Monosaccharides are simple sugars that cannot be broken down into simpler sugars upon hydrolysis. Examples of monosaccharides are glucose, ribose, deoxyribose, and fructose. Disaccharides contain two monosaccharide units and yield two monosaccharides upon hydrolysis. Examples of disaccharides are lactose, maltose, and sucrose. Polysaccharides are polymers of monosaccharide units and yield many individual monosaccharides upon hydrolysis. Examples of polysaccharides are starch, glycogen, and cellulose. 

Monosaccharides, present only in trace amounts in green coffee, increase to 2.6% in roasted coffee due in part to the production of galactose, mannose,103 arabinose, and ribose,104 as the heteropolysaccharides are broken down. 

Reaction of nitromethane and monosaccharide-derived dialdehydes is a useful tool that has been broadly used for the preparation of nitro and amino sugars, and carbocycles.30 Dialdehydes can easily be obtained by oxidative cleavage of conveniently protected monosaccharides with sodium periodate. Their subsequent Henry reaction with a nitroalkene, commonly nitromethane, usually gives isomeric mixtures that require the isolation of the major isomer.31 Thus, treatment of the D-ribose derivative 27 with sodium periodate gave dialdehyde 28, which was subjected to a Henry reaction with nitromethane, to afford nitrosugar 29 as an epimeric mixture (Scheme 11).32... 

DNA incorporates the monosaccharide deoxyribose, while RNA has ribose. One of the four bases is different RNA has uracil in place of thymine in DNA. Finally, RNA has no double helix. 

Carbohydrates Ceiiuiose Starch 1 Hemiceiiuiose Lignin J ( monosaccharides "j ( hexoses "j Cx(H20)y < oligosaccharides > pentoses > [ chitin J ( glucosamine J (C2H20)4 unsaturated aromatic alcohols —> polyhydroxy carboxylic aoids HPOy, GO2, CH4, glucose, fructose, galactose, arabinose, ribose, xylose... 

Six-carbon sugars (hexoses) and five-carbon sugars (pentoses) are the most frequently encountered monosaccharide carbohydrate units in nature. Primary examples of these two classes are the hexoses glucose and fructose, and the pentose ribose. Note the suffix -ose as a general indicator of carbohydrate nature. 

Monosaccharide structures may be depicted in open-chain forms showing their carbonyl character, or in cyclic hemiacetal or hemiketal forms. Alongside the Fischer projections of glucose, ribose, and fructose shown earlier, we included an alternative... 

A 5-carbon monosaccharide (either D-ribose [in RNA] or 2-deoxy-D-ribose [in DNA])... 

In nucleotide structure, the central component is the 5-carbon furanoside monosaccharide, either D-ribose (in RNA) or 2-deoxy-D-ribose (in DNA). The four heterocyclic bases found in DNA-based nucleotides are adenine, guanine, cytosine, and thymine ... 

An almost complete separation of D-glucose from D-ribose on the poly(acrylamide) gel Bio-Gel P-2, with water as the eluant, has been reported by John and coworkers.81 A water-jacketed column (127 X 1.5 cm) at a temperature of 65° and gel of very fine particle-size (400 mesh) were used. Only under such conditions, where resolution is optimal, does good separation of monosaccharides by gel chromatography become possible. 

The structures of two (p-bromophenyl)hydrazones have been determined from projection data. The first was that of D-ribose,112 in which the D-ribose is acyclic, in a sickle18 conformation, and C-l, C-2, C-3, and C-4 are coplanar. Rotation of C-5 out of this plane relieves the 0-2, 0-4 interaction that would be present in the extended conformation and brings 0-5 close to 0-2, so that an intramolecular hydrogen-bond can be formed this is the first (and, thus far, the only) case of an intramolecular hydrogen bond in a crystal of a monosaccharide derivative. The hydroxyl groups on C-2, C-3, and C-4 form three intermolecular hydrogen-bonds. 

Intramolecular hydrogen-bonding between two oxygen atoms in the same monosaccharide is of minor importance in a crystal lattice. Only one example is at present known, namely, in D-ribose (p-bromo-phenyl)hydrazone.l,z... 

If any monosaccharide lacks the usual numbers of hydroxyl groups, it is often caUed a deoxy sugar. For example, 2-deoxyribose, which is a component of DNA nucleosides, has one less hydroxyl group than its parent sugar, ribose. 

Monosaccharides also form phosphate esters with phosphoric acid. Monosaccharide phosphate esters are important molecules in biological system. For example, in the DNA and RNA nucleotides, phosphate esters of 2-deoxyribose and ribose are present, respectively. Adenosine triphosphate (ATP), the triphosphate ester at C-5 of ribose in adenosine, is found extensively in living systems. 

FIGURE 7-1 Representative monosaccharides, (a) Two trioses, an aldose and a ketose. The carbonyl group in each is shaded, (b) Two common hexoses. (c) The pentose components of nucleic acids. D-Ribose is a component of ribonucleic acid (RNA), and 2-deoxy-o-ribose is a component of deoxyribonucleic acid (DNA). 

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