Propionyl-CoA carboxylase has been purified to a state of near nomogeniety, and some of its enzymatic properties relating to substrate binding and mechanism of action have been studied. The enzyme was not found to catalyze the incorporation of solvent tritium at the c-carbon of propionylâ CoA in the absence of ATP. Absolute stereospecificity was observed with regard to which a-hydrogen is replaced during the addition. / Ph. D.