Subunit specificity of the two acetyl-CoA synthetases of yeast as revealed by an immunological approach.

1. In the present paper, the two acetyl-CoA synthetases (acetate:Coenzyme A ligase (AMP-forming), EC 6.2.1.1) elaborated under aerobic or nonaerobic conditions are further differentiated by an immunological approach. 2. The subunit of the aerobic isozyme was prepared and found to be homogeneous by disc gel electrophoresis in the presence of sodium dodecyl sulfate (SDS) and by ultracentrifugal studies. An s20,w of 3.6 and an apparent molecular weight of 80,500 +/- 500 were calculated for this subunit. 3. The subunit was precipitated by antibody prepared against the aerobic enzyme. Antibody prepared against the subunit also reacted in precipitin tests with the subunit, but not with the native enzyme. The latter antibody nevertheless inhibited the native enzyme but not the nonaerobic isozyme.