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Ribulose 1,5-bisphosphate (RuBP) is an organic substance that is involved in photosynthesis, notably as the principal CO 2 acceptor in plants. [ 1 ] : 2 It is a colourless anion, a double phosphate ester of the ketopentose ( ketone -containing sugar with five carbon atoms) called ribulose .
RuBisCO is important biologically because it catalyzes the primary chemical reaction by which inorganic carbon enters the biosphere.While many autotrophic bacteria and archaea fix carbon via the reductive acetyl CoA pathway, the 3-hydroxypropionate cycle, or the reverse Krebs cycle, these pathways are relatively small contributors to global carbon fixation compared to that catalyzed by RuBisCO.
Ribulose-5 phosphate can also be acted upon by phosphopentose epimerase to form xylulose 5-phosphate, which is used in the nonoxidative phase of the pentose phosphate pathway in humans to generate precursor molecules for the synthesis of aromatic amino acids and production of energy.
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 ...
For example, d-ribulose is an intermediate in the fungal pathway for d-arabitol production. Also, as the 1,5-bisphosphate, d-ribulose combines with carbon dioxide at the start of the photosynthesis process in green plants (carbon dioxide trap). [2] Ribulose has the same stereochemistry at carbons 3 and 4 as the five-carbon aldoses ribose and ...
Phosphoribulokinase (PRK) (EC 2.7.1.19) is an essential photosynthetic enzyme that catalyzes the ATP-dependent phosphorylation of ribulose 5-phosphate (RuP) into ribulose 1,5-bisphosphate (RuBP), both intermediates in the Calvin Cycle. Its main function is to regenerate RuBP, which is the initial substrate and CO 2-acceptor molecule of the ...
Ribose 1,5-bisphosphate phosphokinase (EC 2.7.4.23), an enzyme that catalyzes the chemical reaction ATP + ribose 1,5-bisphosphate ADP + 5-phospho-alpha-D-ribose 1-diphosphate Ribulose 1,5-bisphosphate (RuBP), an important substrate involved in carbon fixation
Ribose-5-phosphate isomerase (Rpi) encoded by the RPIA gene is an enzyme (EC 5.3.1.6) that catalyzes the conversion between ribose-5-phosphate (R5P) and ribulose-5-phosphate (Ru5P). It is a member of a larger class of isomerases which catalyze the interconversion of chemical isomers (in this case structural isomers of pentose).