title: Mechanism of action of ribulose bisphosphate carboxylase/oxygenase.
abstract: RuBP carboxylase-oxygenase appears to catalyze carboxylation and oxygenation by homologous mechanisms. A common binding site exists on the enzyme for the acceptor substrate, RuBP. A mechanism is proposed whereby RuBP is isomerized, and a carbanion is generated at C2. Then, either CO2 or O2 is added as an electrophile at C2 to form the corresponding 3-keto-2-carboxy-RBP or 3-keto-2-hydroperoxy-RBP adduct. Hydrolytic cleavage at the C2-C3 bonds of these intermediates by the enzyme is envisioned to produce 2 molecules of 3-phosphoglycerate in the carboxylation sequence and 1 molecule of phosphoglycolate and 1 molecule of 3-phosphoglycerate in the oxygenation sequence. Further work will be necessary to establish the validity of the proposed mechanism.
mesh_terms: D002245:Carbon Dioxide; D002262:Carboxy-Lyases / Q000378:metabolism*; D007700:Kinetics; D008345:Manganese / Q000494:pharmacology; D008970:Molecular Weight; D010944:Plants / Q000201:enzymology; D011485:Protein Binding; D012273:Ribulose-Bisphosphate Carboxylase / Q000302:isolation & purification / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D002245:Carbon Dioxide; D008345:Manganese; D002262:Carboxy-Lyases; D012273:Ribulose-Bisphosphate Carboxylase