    4.1.1.112 | oxaloacetate = pyruvate + CO2 |
catalytic mechanism, overview. Carboxybiotin transits to the membrane-bound beta-subunit where it is decarboxylated to biotin and CO2 in a reaction that consumes a periplasmic proton and is coupled to Na+ translocation from the cytoplasm to the periplasm. The reaction is initiated by the enzyme-catalyzed decarboxylation of oxaloacetate in the carboxyltransferase domain of the alpha-subunit, yielding pyruvate and carboxybiotin. Subsequently, the C-terminal biotin carboxyl carrier protein domain on the alpha-subunit translocates to the beta-subunit where its decarboxylation is coupled to Na+ translocation. The OADC pump is reversible: at high concentrations of extracellular Na+, the pump will couple the downhill movement of Na+ into the cytosol with the carboxylation of pyruvate, to form oxaloacetate |
726821 |
