D-ribose-5-P

Ribose 5-phosphate

Names
IUPAC name (2,3,4-Trihydroxy-5-oxo-pentoxy)phosphonic acid
Identifiers
CAS Number	4300-28-1
3D model (JSmol)	Interactive image
ChEBI	CHEBI:58273 Y
ChemSpider	70368
MeSH	ribose-5-phosphate
PubChem CID	77982
InChI InChI=1S/C5H11O8P/c6-1-3(7)5(9)4(8)2-13-14(10,11)12/h1,3-5,7-9H,2H2,(H2,10,11,12)/t3-,4+,5-/m0/s1  Key: PPQRONHOSHZGFQ-LMVFSUKVSA-N  InChI=1/C5H11O8P/c6-1-3(7)5(9)4(8)2-13-14(10,11)12/h1,3-5,7-9H,2H2,(H2,10,11,12)/t3-,4+,5-/m0/s1 Key: PPQRONHOSHZGFQ-LMVFSUKVBC
SMILES C([C@H]([C@H]([C@H](C=O)O)O)O)OP(=O)(O)O
Properties
Chemical formula	C5H11O8P
Molar mass	230.110
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
(what is Y ?)
Infobox references

Ribose 5-phosphate (R5P) is both a product and an intermediate of the pentose phosphate pathway. The last step of the oxidative reactions in the pentose phosphate pathway is the production of ribulose 5-phosphate. Depending on the body's state, ribulose 5-phosphate can reversibly isomerize to ribose 5-phosphate. Ribulose 5-phosphate can alternatively undergo a series of isomerizations as well as transaldolations and transketolations that result in the production of other pentose phosphates as well as fructose 6-phosphate and glyceraldehyde 3-phosphate (both intermediates in glycolysis).

The enzyme ribose-phosphate diphosphokinase converts ribose-5-phosphate into phosphoribosyl pyrophosphate.

R5P consists of a five-carbon sugar, ribose, and a phosphate group at the five-position carbon. It can exist in open chain form or in furanose form. The furanose form is most commonly referred to as ribose 5-phosphoric acid.

The formation of R5P is highly dependent on the cell growth and the need for NADPH (Nicotinamide adenine dinucleotide phosphate), R5P, and ATP (Adenosine triphosphate). Formation of each molecule is controlled by the flow of glucose 6-phosphate (G6P) in two different metabolic pathways: the pentose phosphate pathway and glycolysis. The relationship between the two pathways can be examined through different metabolic situations.

R5P is produced in the pentose phosphate pathway in all organisms. The pentose phosphate pathway (PPP) is a metabolic pathway that runs parallel to glycolysis. It is a crucial source for NADPH generation for reductive biosynthesis (e.g. fatty acid synthesis) and pentose sugars. The pathway consists of two phases: an oxidative phase that generates NADPH and a non-oxidative phase that involves the interconversion of sugars. In the oxidative phase of PPP, two molecules of NADP+ are reduced to NADPH through the conversion of G6P to ribulose 5-phosphate (Ru5P). In the non-oxidative of PPP, Ru5P can be converted to R5P through ribose-5-phosphate isomerase enzyme catalysis.