Models and mechanisms of cytochrome P450 action

11. Conclusion: Cytochrome P450 has been called the Rosetta Stone of iron proteins. Perhaps nowhere else in the biological sciences has the rich interplay between structural, spectroscopic, mechanistic, computational, and chemical modeling techniques led to such a detailed level of understanding of such an important system. The central paradigm of biological oxygen activation is now recognized to involve the formation a ferryl, or oxoiron intermediate. Oxoiron(IV) porphyrin cation radicals have been observed in peroxidase, cytochrome oxidase, CPO, cytochrome P450, and in a variety of model systems. Model system studies, especially those of iron, manganese, and ruthenium porphyrins and related ligands, have led to important advances in catalysis and in catalytic asymmetric oxygenation. Advances in computational studies of such complex, open-shell systems have begun to provide a rigorous physical underpinning for the body of complex and sometimes confusing experimental results. In this chapter, I have tried to weave together all of these aspects to provide for the reader a unified picture of the current understanding in the field of cytochrome P450 research. More detailed presentations are to be found in the chapters that follow.