Propionyl‐coenzyme A carboxylase of Mycobacterium smegmatis

Abstract
Propionyl-CoA carboxylase was purified to homogeneity and examined by EM. The native carboxylase presents a profile with a large central subunit to which smaller subunits are attached. The central subunit has 2 prominent profiles, 1 circular (100 .ANG.) with a central hole and the other rectangular (70 .times. 100 .ANG.). The 6 polypeptides of this subunit appear to be arranged in a cylindrical structure. Six spherical (50 .ANG.) biotin-containing peripheral subunits are attached in sets of 3 to the 2 opposite circular faces of the central subunit. A model of the 18-S carboxylase is presented.