Mechanistic Implications of the Oxo-Iron Structure

Given the strong evidence for an oxo-iron structure containing a short Fe=0 double bond, of 1.65 A in high-valent states of a number of heme proteins, one then questions the functional significance of this species as an enzymatic intermediate. The close similarity in structure between horseradish 

Finally, the similarity between the peroxidases, especially chloroperoxidase, and cytochrome P-450 in their reactivity with peroxide suggests that the active oxygen species in P-450 may also be a ferryl species, i.e., an oxo iron (TV) complex. Evidence both for [193] and against [194] the involvement of a Compound I-type intermediate in the reaction cycle of P-450 has appeared. As of yet, there exists no direct evidence for the nature of the intermediates beyond oxy-P-450 in the reaction cycle. 

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