Ribose

D-Ribose
IUPAC name D-Ribose
Identifiers
CAS number	50-69-1 Y
PubChem	5779
EC-number	200-059-4
DrugBank	DB01936
ChEMBL	CHEMBL1159662 N
Properties[1][2]
Molecular formula	C5H10O5
Molar mass	150.13 g/mol
Appearance	white solid
Melting point	95 °C, 368 K, 203 °F
Solubility in water	very soluble
Chiral rotation [α]D	−21.5º (H2O)
Related compounds
Related aldopentoses	Arabinose Xylose Lyxose
Related compounds	Deoxyribose
N (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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 any of two enantiomers: almost always 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 enantiomer 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 comprises 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, that is 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 in carbon C2'.

Like many monosaccharides, ribose occurs in water as the linear form H–(C=O)–(CHOH)₄–H and any of two ring forms: ribofuranose ("C3'-endo"), with a five-membered ring, and ribopyranose ("C2'-endo"), with a six-membered ring. The ribofuranose form is predominant in aqueous solution.

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).^[4]

References

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. doi:10.1002/sce.3730420523. 
4. ^ [1]^{[dead link]}