Separation of active enzyme components from the fatty acid synthetase of chicken liver.

Fatty acid synthetase (EC 6.2.1.-) of chicken liver was dissociated into half-size subcomplexes and then separated into three protein fractions by the preparative disc-gel electrophoresis technique. The anodal protein (Fa) of a molecular weight of approx. 6000 contains the prosthetic group, 4'-phosphopantetheine. It binds acetyl group from acetyl-CoA and is identified as the acyl carrier protein component. The slower moving proteins (FI and FII) correspond to the subcomplexes resolved by the analytical method (Y.n, S.L. and Hsu, R.Y. (1972) J. Biol. Chem 247, 2689--2698). Both contain acetyl transacylase and palmityl-CoA deacylase activities, but only FI contains beta-ketoacyl reductase activity. Active acetyl transacylase and palmityl-CoA deacylase components were obrained by the sucrose density centrifugation technique in a broad 3 S protein band from the FI fraction, following dissociation at 4 degrees C for 12 days. Slight modification of the electrophoresis conditions yields a homogeneous 1.55 S beta-ketoacyl reductase component.