Cyanobacterial aldehyde-deformylating oxygenase (ADO) catalyzes the second of two enzymatic reactions that convert abundant Cn fatty acids into Cn-1 diesel-fuel alk(a/e)nes.1 ADO is a ferritin-like diiron-carboxylate1 oxygenase3,4 that uses O2 and four electrons to convert its aldehyde substrate to formate and the alk(a/e)ne (Scheme ).2-4 The enzyme�aldehyde complex (A ) reacts rapidly with O2 to make an intermediate with properties consistent with a diiron(III/III)-peroxyhemiacetal structure (C ).5 O-O-bond cleavage by electron transfer from the requisite reducing system (e� downward ) may produce an O-centered 'gem-diolyl' radical (D ), which may initiate C1-C2 radical fragmentation to formate and the Cn-1 methylene product radical (E ).6 Transfer of H� to this radical and electron transfer from the reducing system (e� leftward ) would complete the oxidative half-reaction (F ); reduction of the cofactor (2e� upward ) would complete the cycle.3-5 Current efforts focus on identification and structural characterization of the key components of this novel cycle, including the diiron-O2 intermediate, the H� donor to the product radical, and the native reducing system.References (1) Schirmer, et al. Science 2010  , 329, 559.(2) Warui, et al. J. J. Am. Chem. Soc. 2011  , 133, 3316.(3) Li, et al. J. Am. Chem. Soc. 2011  , 133, 6158.(4) Li, et al. Biochemistry 2012  , 51, 7908.(5) Pandelia, et al. J. Am. Chem. Soc. 2013  , 135, 15801.(6) Paul, et al. J. Am. Chem. Soc. 2013  , 135, 5234.

Fatty acids to diesel fuel: The mechanism of the cryptically redox oxygenation reaction of aldehyde deformylating oxygenase

247th National Meeting (2014)

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