Ribose: Difference between revisions

D-Ribose
Names
	IUPAC name (2S,3S,4S,5R)-5-(hydroxymethyl)oxolane-2,3,4-triol
Identifiers
CAS Number	50-69-1 ;
ChEMBL	ChEMBL1159662 ;
DrugBank	DB01936 ;
PubChem CID	5779;
Properties
Chemical formula	C5H10O5
Molar mass	150.13 g/mol
Appearance	white solid
Melting point	95 °C (203 °F; 368 K)
Solubility in water	very soluble
Chiral rotation ([α]D)	−21.5° (H2O)
Related compounds
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

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a Ribose is an organic compound with the formula C₅H₁₀O₅; specifically, a monosaccharide (simple sugar) with linear form H−(C=O)−(CHOH)₄−H, which has all the hydroxyl groups on the same side in the Fischer projection.

The term may refer to either of two enantiomers: it almost always refers to D-ribose, which occurs widely in nature and is discussed here; or to its synthetic mirror image L-ribose, which is not found in nature and is of limited interest.

D-Ribose was first reported in 1891 by Emil Fischer. It is a C'-2 carbon epimer of the sugar D-arabinose (both isomers of which are named for their source, gum arabic) and ribose itself is named as a transposition of the name of arabinose.^[3]

Ribose constitutes the backbone of RNA, a biopolymer that is the basis of genetic transcription. It is related to deoxyribose, as found in DNA. Once phosphorylated, ribose can become a subunit of ATP, NADH, and several other compounds that are critical to metabolism like the secondary messengers cAMP and cGMP.

Structure

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 C1' (in the aldehyde group) to C5'. The deoxyribose derivative found in DNA differs from ribose by having a hydrogen atom in place of the hydroxyl group at C2'.

Like many monosaccharides, ribose exists in an equilibrium among 5 forms--the linear form H−(C=O)−(CHOH)₄–H and either of the two ring forms: alpha- or beta-ribofuranose ("C3'-endo"), with a five-membered ring, and alpha- or beta-ribopyranose ("C2'-endo"), with a six-membered ring. The beta-ribopyranose form predominates in aqueous solution.^[4]

The "D-" in the name D-ribose refers to the stereochemistry of the chiral carbon atom farthest away from the aldehyde group (C4'). In D-ribose, as in all D-sugars, this carbon atom has the same configuration as in D-glyceraldehyde.

Phosphorylation

In biology, D-ribose must be phosphorylated by the cell before it can be used. Ribokinase catalyzes this reaction by converting D-ribose to D-ribose 5-phosphate. Once converted, D-ribose-5-phosphate is available for the manufacturing of the amino acids tryptophan and histidine, or for use in the pentose phosphate pathway. The absorption of D-ribose is 88–100% in the small intestines (up to 200 mg/kg/hr).^[5]

References

^ The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (11th ed.), Merck, 1989, ISBN 091191028X, 8205.
^ Weast, Robert C., ed. (1981). CRC Handbook of Chemistry and Physics (62nd ed.). Boca Raton, FL: CRC Press. p. C-506. ISBN 0-8493-0462-8..
^ Nechamkin, Howard (1958). "Some interesting etymological derivations of chemical terminology". Science Education. 42: 463. Bibcode:1958SciEd..42..463N. doi:10.1002/sce.3730420523.
^ Angyal, S. J. (1969). "The Composition and Conformation of Sugars in Solution". Angewandte Chemie. 8 (3): 157–166. doi:10.1002/anie.196901571. Retrieved 5 June 2012. {{cite journal}}: Unknown parameter |month= ignored (help)
^ [1]^{[dead link]}

[1] The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (11th ed.), Merck, 1989, ISBN 091191028X, 8205.

[2] Weast, Robert C., ed. (1981). CRC Handbook of Chemistry and Physics (62nd ed.). Boca Raton, FL: CRC Press. p. C-506. ISBN 0-8493-0462-8..

[3] Nechamkin, Howard (1958). "Some interesting etymological derivations of chemical terminology". Science Education. 42: 463. Bibcode:1958SciEd..42..463N. doi:10.1002/sce.3730420523.

[4] Angyal, S. J. (1969). "The Composition and Conformation of Sugars in Solution". Angewandte Chemie. 8 (3): 157–166. doi:10.1002/anie.196901571. Retrieved 5 June 2012. {{cite journal}}: Unknown parameter |month= ignored (help)

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-'''Ribose''' is an [[organic compound]] with the formula C<sub>5</sub>H<sub>10</sub>O<sub>5</sub>; specifically, a [[monosaccharide]] (simple [[sugar]]) with linear form H−(C=O)−(CHOH)<sub>4</sub>−H, which has all the [[hydroxyl]] groups on the same side in the [[Fischer projection]].
+a '''Ribose''' is an [[organic compound]] with the formula C<sub>5</sub>H<sub>10</sub>O<sub>5</sub>; specifically, a [[monosaccharide]] (simple [[sugar]]) with linear form H−(C=O)−(CHOH)<sub>4</sub>−H, which has all the [[hydroxyl]] groups on the same side in the [[Fischer projection]].
 The term may refer to either of two [[enantiomer]]s: it almost always refers to '''<small>D</small>-ribose''', which occurs widely in nature and is discussed here; or to its synthetic mirror image '''<small>L</small>-ribose''', which is not found in nature and is of limited interest.