Haem-oxygen reactive intermediates: catalysis by the two-step.

The catalytic schemes of a variety of haem enzymes, including the P450 mono-oxygenases, consist of a number of common reactive haem-oxygen adducts. The characterization of these intermediates by optical and EPR spectroscopies has reinforced the similarity of these intermediate states in a number of haem enzyme systems. Furthermore, the reactivity of these states in P450 and horseradish peroxidase, in which multiple potent oxidants are formed, provides a paradigm for many other haem enzymes.