Rapid reduction of the oxyform of cytochrome P450 by a hydrated electron

What is it about?

The reaction mechanism of cytochrome P450 is difficult to investigate, because the enzymic reduction is rate-limiting. Steps after the reduction of the oxyform are not observable. The canonical reaction mechanism is based on low-temperature and isotope studies.

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Why is it important?

By pulse radiolysis one generates a powerful reductant, the hydrated electron. It reduces the oxyform of cytochrome P450 in microseconds, which allowed us to see the iron(III) - hydrogen peroxide intermediate, but not the formation of Compounds I and II, which are formed and decay very fast. This observation allowed us to set limits on the activation energies, and to complete the thermodynamics of the hydroxylation of camphor. The yield of hydroxycamphor was quantitative.