Carbon monoxide binding by Pseudomonas putida cytochrome P-450

Abstract

The interaction of carbon monoxide with Pseudomonas putida cytochrome P-450 is affected by the substrate camphor. In the presence of camphor, the equilibrium constant for the reaction with carbon monoxide is 2.6 × 10 5 m −1 while in the absence of camphor the equilibrium constant is 2.2 × 10 6 m −1. The second-order reaction rate constant for the reaction of carbon monoxide with the camphor complex of ferrous cytochrome P-450 is 3.8 × 10 4 m −1 sec −1, while in the absence of camphor the second-order reaction rate constant is 5.1 × 10 6 m −1 sec −1. The results presented support the conclusion that camphor is bound to ferrous cytochrome P-450 at a site which markedly modifies the carbon monoxide (oxygen) binding site on the heme iron atom.