[Effect of lipids and substrates on the kinetics of binding of ferrocytochrome P-450 to CO].

Using the flash photolysis technique, it was found that the kinetics of recombination of carbon monoxide with ferrocytochrome P-450 LM-2 can be approximated by the sum of three exponents. Incorporation of cytochrome P-450 into liposomes prepared from microsomal lipids leads to the reduction of the number of steps to two as well as to essential changes in rate constants. Addition of type I substrates (Triton N-101, albumin) cause similar changes in the reaction kinetics. NADPH-cytochrome P-450 reductase has no effect on this process. The multistep kinetics of CO recombination with cytochrome P-450 LM-2 may be accounted for by the presence of some protein conformers. The experimental results suggest that the activity and structure of cytochrome P-450 conformers is affected by the lipid microenvironment, type I substrates and Triton N-101.