Chicken liver fatty acid synthetase is inactivated by malonyl CoA. The rate and extent of inactivation depends upon the ratio of concentration of malonyl CoA to enzyme rather than the absolute concentrations. The rate of inactivation is enhanced by acetyl CoA but is slowed down by NADP+. Inactivation does not result in the dissociation of enzyme complex and is complete when 6–7 moles of malonyl group are covalently bound per mole of the enzyme.