Methane monooxygenase (MMO), 1, 2 stearoyl ACP Δ9-desaturase (Δ9D), 3 and ribonucleotide reductase (RNR) 4, 5 comprise a new class of metalloenzymes that activate dioxygen at a nonheme diiron active site6 to carry out diverse functions such as the hydroxylation of methane, the desaturation of saturated fatty acids, and the generation of the catalytically essential Tyr radical for ribonucleotide reduction. The mechanisms for ...
