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. Author manuscript; available in PMC: 2018 Aug 28.
Published in final edited form as: Chem Rev. 2017 Dec 22;118(4):1460–1494. doi: 10.1021/acs.chemrev.7b00510

Figure 15.

Figure 15

Two main types of iron-based monooxygenases: (a) heme-based Cytochromes P450 use high valent ferryl oxygen intermediates as strong oxidants for one electron chemistry to effect C-H bond homolysis at unactivated carbon sites and OH• rebound for net hydroxylation; (b) the maturation of arachidonate into PGG2 and PGH2 involves an initial allyl radical conversion to a pair of peroxy radicals one of whch closes to the cyclopentane endoperoxide characteristic of PGG2 and PGH2; (c) the typical two His, one Glu/Asp coordination set for nonheme mononuclear iron oxygenases also includes cosubstrate α-ketoglutarate as the 4th and 5th ligands to Fe. An analogous FeIV=O high valent oxoiron species performs comparable homolytic C-H bond cleavage and OH• equivalent transfer; (d) oxidative demethylation of 5-MeC residues in DNA is mediated by the TET subfamily of nonheme mononuclear iron oxygenases, in three sequential steps as shown.