Ribulose bisphosphate carboxylase large chain, Form III
Ribulose bisphosphate carboxylase (Rubisco) plays an important role in the Calvin reductive pentose phosphate pathway. It catalyzes the primary CO2 fixation step. Rubisco is activated by carbamylation of an active site lysine, stabilized by a divalent cation, which then catalyzes the proton abstraction from the substrate ribulose 1,5 bisphosphate (RuBP) and leads to the formation of two molecules of 3-phosphoglycerate. Members of the Rubisco family can be divided into 4 subgroups, Form I-IV , which differ in their taxonomic distribution and subunit composition. Form III is only found in archaea and forms large subunit oligomers (dimers or decamers) that do not include small subunits.
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