3mkh
From Proteopedia
Podospora anserina Nitroalkane Oxidase
Structural highlights
FunctionNAO_PODAN Nitroalkane oxidase (NAO) catalyzes the oxidation of nitroalkanes to the corresponding aldehydes or ketones with the release of nitrite and the consumption of molecular oxygen to yield hydrogen peroxide (PubMed:20481475). NAO is unusual, since it catalyzes substrate oxidation by removing a substrate proton to form a carbanion intermediate (PubMed:20481475). Prefers longer nitroalkanes, with 1-nitrohexane having the highest activity (PubMed:20481475).[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe flavoprotein nitroalkane oxidase (NAO) from Fusarium oxysporum catalyzes the oxidation of primary and secondary nitroalkanes to their respective aldehydes and ketones. Structurally, the enzyme is a member of the acyl-CoA dehydrogenase superfamily. To date no enzymes other than that from F. oxysporum have been annotated as NAOs. To identify additional potential NAOs, the available database was searched for enzymes in which the active site residues Asp402, Arg409, and Ser276 were conserved. Of the several fungal enzymes identified in this fashion, PODANSg2158 from Podospora anserina was selected for expression and characterization. The recombinant enzyme is a flavoprotein with activity on nitroalkanes comparable to the F. oxysporum NAO, although the substrate specificity is somewhat different. Asp399, Arg406, and Ser273 in PODANSg2158 correspond to the active site triad in F. oxysporum NAO. The k(cat)/K(M)-pH profile with nitroethane shows a pK(a) of 5.9 that is assigned to Asp399 as the active site base. Mutation of Asp399 to asparagine decreases the k(cat)/K(M) value for nitroethane over 2 orders of magnitude. The R406K and S373A mutations decrease this kinetic parameter by 64- and 3-fold, respectively. The structure of PODANSg2158 has been determined at a resolution of 2.0 A, confirming its identification as an NAO. Identification of a Hypothetical Protein from Podospora anserina as a Nitroalkane Oxidase.,Tormos JR, Taylor AB, Daubner SC, Hart PJ, Fitzpatrick PF Biochemistry. 2010 May 27. PMID:20481475[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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