The inactivation of horseradish peroxidase by m-chloroperoxybenzoic acid, a xenobiotic hydroperoxide

• Published in: Journal of molecular catalysis. A, Chemical Vol. 104; no. 2; pp. 179 - 191
• Main Authors: Arnao, M.B., Hernández-Ruiz, J., Varón, R., García-Cánovas, F., Acosta, M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.12.1995; Elsevier
• Subjects: Analytical, structural and metabolic biochemistry; Biological and medical sciences; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Hydroperoxide; Inactivation; Kinetics; Oxidoreductases; Peroxidase; m-CPBA; m-CBA; HRP; Hydroperoxide; Peroxidase; Kinetics; Inactivation; ABTS; Substrate; Horse radish; Peroxidases; Enzyme; Enzyme inhibitor; Oxidoreductases; Oxidant; Kinetic parameter; Peroxidation
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/1381-1169(95)00114-X

m-Chloroperoxybenzoic acid ( m-CPBA) acts as an oxidant substrate of peroxidase (EC 1.11.1.7) and, at the same time, is a powerful suicide substrate of the enzyme. A value for the partition ratio ( r) between the catalytic and the inactivating routes is calculated in the absence of the typical reductant substrates of peroxidase: One mole of enzyme gives around two turnovers ( r = 1.8 ± 0.1). The kinetic analysis allows us to calculate a value for the inactivation constant k i = (4.80 ± 0.40) · 10 −3 s −1, being very similar to that obtained for H 2O 2. These results suggest that, contrary to H 2O 2, in the case of m-CPBA a catalase-like reaction is not active and so the enzyme is not protected. Also, the calculated value for K 2 (6.54 μM) indicates a high affinity of Compound I for m-CPBA.