Characterization of 2-oxo-3-pentynoate as an active-site-directed inactivator of flavoprotein oxidases: identification of active-site peptides in tryptophan 2-monooxygenase

2-Oxo-3-pentynoate was found to be an active-site-directed inhibitor of certain flavoprotein oxidases. Tryptophan 2-monooxygenase is irreversibly inactivated in an active-site-directed manner. The addition of FAD provides no protection from inactivation, while the competitive inhibitor indole-3-acetamide fully protects the enzyme from inactivation. The rate of inactivation indicates saturation kinetics, consistent with the production of a reversible complex between the alkylating agent and the enzyme before inactivation occurs.