Ribulose-1,5-bisphosphate

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Ribulose-1,5-bisphosphate
Skeletal formula of RuBP
Ball-and-stick model, based on x-ray diffraction data
Identifiers
ChemSpider 110238 YesY
ChEBI CHEBI:16710 YesY
Jmol-3D images Image 1
Properties
Molecular formula C5H12O11P2
Molar mass 310.09 g mol−1
Except where noted otherwise, 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. The anion is a double phosphate ester of the ketose (ketone-containing sugar) called ribulose. Salts of this species can be isolated, but its crucial biological function involves this colourless anion in solution.[1] To simplify the presentation, the image in the above table depicts the acid form of this anion.

Role in photosynthesis[edit]

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

The enzyme ribulose bisphosphate carboxylase oxygenase (RuBisCO) catalyzes the reaction between RuBP with 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. RuBP is also involved in photorespiration, in which is combines with O2 to become PGA+ Phosphoglycolic Acid. In the Calvin Cycle, RuBP is a product of the phosphorylation of ribulose-5-phosphate by ATP.

References[edit]

  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.