High-pressure effect on the equilibrium and kinetics of cyanide binding to chloroperoxidase |
| |
Authors: | A M Lambeir K Heremans H B Dunford |
| |
Institution: | 1. Laboratorium voor Chemische en Biologische Dynamica, Katholieke Universiteit te Leuven, B - 3030 Leuven, Belgium;2. Department of Chemistry, University of Alberta, Eamonton, Alberta, T6G 2G2, Canada |
| |
Abstract: | The kinetics of cyanide binding to chloroperoxidase were studied using a high-pressure stopped-flow technique at 25 degrees C and pH 4.7 in a pressure range from 1 to 1000 bar. The activation volume change for the association reaction is delta V not equal to + = -2.5 +/- 0.5 ml/mol. The total reaction volume change, determined from the pressure dependence of the equilibrium constant, is delta V degrees = -17.8 +/- 1.3 ml/mol. The effect of temperature was studied at 1 bar yielding delta H not equal to + = 29 +/- 1 kJ/mol, delta S not equal to + = -58 +/- 4 J/mol per K. Equilibrium studies give delta H degrees = -41 +/- 3 kJ/mol and delta S degrees = -59 +/- 10 J/mol per K. Possible contributions to the binding process are discussed: changes in spin state, bond formation and conformation changes in the protein. An activation volume analog of the Hammond postulate is considered. |
| |
Keywords: | Pressure effect: Cyanide binding: Chloroperoxidase: Actication volume: Hammond postulate: (Caldariomyces fumago) |
本文献已被 ScienceDirect PubMed 等数据库收录! |
|