The pH 6 Acetolactate-forming Enzyme from Aerobacter aerogenes

An investigation of the requirement of the pH 6 acetolactate-forming enzyme for FAD has been performed with a recrystallized preparation of the enzyme. The following criteria indicate that the pH 6 acetolactate-forming enzyme is not a flavoprotein. 1. The addition of FAD to the enzyme assay did not stimulate the formation of acetolactate. 2. No FAD was released from the enzyme after trichloracetic acid treatment. 3. The absorption of the enzyme at 375 mµ and at 450 mµ did not indicate the presence of FAD bound to the enzyme.