The Role of Biotin in Carboxylation Reactions

The biotin-dependent carboxylases catalyze a two-step reaction [Pg.330]

enzyme-biotin + ATP + HCOs - enzyme-biotin-COOH + ADP + P [Pg.330]

enzyme-biotin- COOH + acceptor enzyme-biotin + acceptor-COOH. [Pg.330]

In the bactericd biotin-dependent decarboxylases, reaction 2 proceeds from right to left, followed by decomposition of the carboxy-biotin to biotin and CO2. [Pg.330]

The role of ATP in the carboxylation of biotin is unclear. It is possible that biotin is O-phosphorylated during the carboxylation reaction. However, evidence suggests that the immediate reactive species that Ccirboxylates biotin is carboxyphosphate, as in the (biotin-independent) reaction of Ccubcunyl phosphate synthetase in urea and pyrimidine synthesis. [Pg.330]

enzyme-biotin - - ATP - - HCO3 enzyme-biotin-COOH - - ADP - - Pj [Pg.330]

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