The cytoplasmic NADP-dependent isocitrate dehydrogenase inhibition by long chain free fatty acids and palmityl-CoA was revealed: 1. In a Tris-citrate buffer, palmityl-CoA inhibited strongly but the free fatty acids hardly at all; whereas, the converse occurred in a glycylglycine buffer. 2. In both instances, the inhibitory effects were competitive with the substrate.
