Oxygenases: mechanisms and structural motifs for O(2) activation.

Recent structural and mechanistic analysis of oxygenase enzymes together with the study of biomimetic model reactions have provided new insights into the catalytic mechanisms of oxygenase-catalysed reactions. High-valent iron-oxo intermediates have been implicated in heme- and pterin-dependent mono-oxygenases. Structural motifs have been identified for binding of non-heme iron(II) (His,His,Glu) and iron(III) (His(2)Tyr(2)) in non-heme-dependent dioxygenases, but additional factors influencing the choice of reaction pathway are emerging from model studies.