Dissociation and reconstitution of the stable multienzyme complex fatty acid synthetase from yeast.

This multienzyme complex behaves during protein fractionation, centrifugation, and electrophoresis as a single protein particle of molecular weight 2.3 x 106 (ref. [ 11). The synthesis of fatty acids requires at least six different enzymatic steps which have been demonstrated with the help of model substrates [2]. After transfer of acetyland malonyl-residues from acetylCoA and malonyl-CoA to thiol acceptor groups of the enzyme complex, condensation results in acetoacetylenzyme. Reduction with NADPH to /3-hydroxybutyryl-enzyme, dehydration to crotonylenzyme and flavin catalyzed reduction to butyrylenzyme ends the first cycle of synthesis. The enzyme-bound butyryl residue is further elongated to the C,-acid by introduction of another malonyl-unit and a second cycle of reactions. After seven or eight such cycles the synthetic process is terminated by transfer of pahnitoylor stearoyl-residues to coenzyme A [3].