Ribulose-1,5-bisphosphate

Ribulose-1,5-bisphosphate

Identifiers
CAS Number	14689-84-0
ChEBI	CHEBI:16710
ChemSpider	110238
Jmol interactive 3D	Image
InChI InChI=1S/C5H12O11P2/c6-3(1-15-17(9,10)11)5(8)4(7)2-16-18(12,13)14/h3,5-6,8H,1-2H2,(H2,9,10,11)(H2,12,13,14)/t3-,5-/m1/s1 Key: YAHZABJORDUQGO-NQXXGFSBSA-N
SMILES O=P(O)(OCC(=O)[C@H](O)[C@H](O)COP(=O)(O)O)O
Properties
Chemical formula	C5H12O11P2
Molar mass	310.09 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Ribulose-1,5-bisphosphate (RuBP) is an organic substance that is involved in photosynthesis. It is a colourless anion. a double phosphate ester of the ketose (ketone-containing sugar) called ribulose. Salts of RuBP can be isolated, but its crucial biological function happens in solution.^[1] To simplify the presentation, the image in the above table depicts the acid form of this anion.

Role in photosynthesis

The Calvin cycle showing the role of ribulose-1,5-bisphosphate.

The enzyme ribulose bisphosphate carboxylase oxygenase (RuBisCO) catalyzes the reaction between RuBP and carbon dioxide. The product is the highly unstable 6-carbon intermediate known as 3-keto-2-carboxyarabinitol 1,5-bisphosphate. This six-carbon intermediate decays virtually instantaneously into two molecules of 3-phosphoglycerate (3-PGA) (see figure). RuBisCO also catalyzes RuBP with oxygen (O2) in a process called photorespiration, a process that is more prevalent at high temperatures. During photorespiration RuBP combines with O2 to become 3-PGA + phosphoglycolic acid. In the Calvin Cycle, RuBP is a product of the phosphorylation of ribulose-5-phosphate by ATP.

References

1. The topic is discussed in all biochemistry textbooks, this one is representative: Nelson, D. L.; Cox, M. M. "Lehninger, Principles of Biochemistry" 3rd Ed. Worth Publishing: New York, 2000. ISBN 1-57259-153-6.