Kinetic study of the oxidative dehalogenation of 2,4,6-trichlorophenol catalyzed by chloroperoxidase

A sigmoidal behaviour of chloroperoxidase for the oxidative dehalogenation of 2,4,6-trichlorophenol is reported for the first time. Kinetic data were adjusted to the Hill equation and the kinetic parameters were obtained: n = 1.7 +/- 0.2, v(max) = (8.8 +/- 0.3) x 10(-5) M min(-1), the pseudo-Michaelis constant K-s*= (8.6 +/- 0.5) x 10(-5) M, k(cat) = 677 +/- 84 min(-1) and the catalytic efficiency = (8.9 +/- 0.6) x 10(6) M-1 min(-1) The sigmoidal curve could be related to the cooperative binding of the substrate to the enzyme, so that the binding of the first substrate molecule may help the binding of the second one. Further, both substrate molecules could establish Pi-Pi interactions between them, which would confer more stability to the system. (C) 2010 Elsevier B.V. All rights reserved.