Kinetics of elementary steps in the cytochrome P-450 reaction sequence. V. Laser temperature-jump investigation of the spin relaxation kinetics of cytochrome P-450 LM2.

The cytochrome P-450 LM2 spin state relaxation kinetics has been resolved by means of laser temperature-jump techniques. The first order rate constants amount to about 10(6) S-1 in the substrate-free and the substrate-bound protein, respectively. Evidence is provided that the spin equilibrium preequilibrates the P-450 reduction but is not rate-limiting. Additional capacitor discharge temperature-jump studies elucidate substrate dependent perturbations.