» Articles » PMID: 22258082

A Complete Volume Profile for the Reversible Binding of Camphor to Cytochrome P450(cam)

Overview
Publisher Springer
Specialty Biochemistry
Date 2012 Jan 20
PMID 22258082
Authors
Affiliations
Soon will be listed here.
Abstract

The effect of pressure on the kinetics and thermodynamics of the reversible binding of camphor to cytochrome P450(cam) was studied as a function of the K(+) concentration. The determination of the reaction and activation volumes enabled the construction of the first complete volume profile for the reversible binding of camphor to P450(cam). Although the volume profiles constructed for the reactions conducted at low and high K(+) concentrations are rather similar, and both show a drastic volume increase on going from the reactant to the transition state and a relatively small volume change on going from the transition to the product state, the position of the transition state is largely affected by the K(+) concentration in solution. Similarly, the activation volume determined for the dissociation of camphor is influenced by the presence of K(+), which reflects changes in the ease of water entering the active site of camphor-bound P450(cam) that depends on the K(+) concentration. Careful analysis of the components that contribute to the observed volume changes allowed the estimation of the total number of water molecules expelled to the bulk solvent during the binding of camphor to P450(cam) and the subsequent spin transition. The results are discussed in reference to other studies reported in the literature that deal with the kinetics and thermodynamics of the binding of camphor to P450(cam) under various reaction conditions.

References
1.
Griffin B, Peterson J . Camphor binding by Pseudomonas putida cytochrome P-450. Kinetics and thermodynamics of the reaction. Biochemistry. 1972; 11(25):4740-6. DOI: 10.1021/bi00775a017. View

2.
Behera R, Mazumdar S . Roles of two surface residues near the access channel in the substrate recognition by cytochrome P450cam. Biophys Chem. 2008; 135(1-3):1-6. DOI: 10.1016/j.bpc.2008.02.016. View

3.
Lange R, Hui Bon Hoa G, Debey P, GUNSALUS I . Ionization dependence of camphor binding and spin conversion of the complex between cytochrome P-450 and camphor. Kinetic and static studies at sub-zero temperatures. Eur J Biochem. 1977; 77(3):479-85. DOI: 10.1111/j.1432-1033.1977.tb11689.x. View

4.
Deprez E, Gerber N, Di Primo C, Douzou P, Sligar S, Hui Bon Hoa G . Electrostatic control of the substrate access channel in cytochrome P-450cam. Biochemistry. 1994; 33(48):14464-8. DOI: 10.1021/bi00252a012. View

5.
Hui Bon Hoa G, Marden M . The pressure dependence of the spin equilibrium in camphor-bound ferric cytochrome P-450. Eur J Biochem. 1982; 124(2):311-5. DOI: 10.1111/j.1432-1033.1982.tb06593.x. View