PDBsum entry 3d9e

Oxidoreductase

PDB id: 3d9e

Contents

Protein chains

431 a.a.

Ligands

FAD ×4

N8C ×4

GOL ×4

Waters ×273

References listed in PDB file

Key reference

• Title: Crystal structures of intermediates in the nitroalkane oxidase reaction.
• Authors: A.Héroux, D.M.Bozinovski, M.P.Valley, P.F.Fitzpatrick, A.M.Orville.
• Ref.: Biochemistry, 2009, 48, 3407-3416.
• PubMed id: 19265437

Abstract

The flavoenzyme nitroalkane oxidase is a member of the acyl-CoA dehydrogenase superfamily. Nitroalkane oxidase catalyzes the oxidation of neutral nitroalkanes to nitrite and the corresponding aldehydes or ketones. Crystal structures to 2.2 A resolution or better of enzyme complexes with bound substrates and of a trapped substrate-flavin adduct are described. The D402N enzyme has no detectable activity with neutral nitroalkanes [Valley, M. P., and Fitzpatrick, P. F. (2003) J. Am. Chem. Soc. 125, 8738-8739]. The structure of the D402N enzyme crystallized in the presence of 1-nitrohexane or 1-nitrooctane shows the presence of the substrate in the binding site. The aliphatic chain of the substrate extends into a tunnel leading to the enzyme surface. The oxygens of the substrate nitro group interact both with amino acid residues and with the 2'-hydroxyl of the FAD. When nitroalkane oxidase oxidizes nitroalkanes in the presence of cyanide, an electrophilic flavin imine intermediate can be trapped [Valley, M. P., Tichy, S. E., and Fitzpatrick, P. F. (2005) J. Am. Chem. Soc. 127, 2062-2066]. The structure of the enzyme trapped with cyanide during oxidation of 1-nitrohexane shows the presence of the modified flavin. A continuous hydrogen bond network connects the nitrogen of the CN-hexyl-FAD through the FAD 2'-hydroxyl to a chain of water molecules extending to the protein surface. Together, our complementary approaches provide strong evidence that the flavin cofactor is in the appropriate oxidation state and correlates well with the putative intermediate state observed within each of the crystal structures. Consequently, these results provide important structural descriptions of several steps along the nitroalkane oxidase reaction cycle.

Secondary reference #1

• Title: Crystal structures of nitroalkane oxidase: insights into the reaction mechanism from a covalent complex of the flavoenzyme trapped during turnover.
• Authors: A.Nagpal, M.P.Valley, P.F.Fitzpatrick, A.M.Orville.
• Ref.: Biochemistry, 2006, 45, 1138-1150. [DOI no: 10.1021/bi051966w]
• PubMed id: 16430210

Secondary reference #2

• Title: Mechanistic and structural analyses of the roles of arg409 and asp402 in the reaction of the flavoprotein nitroalkane oxidase.
• Authors: P.F.Fitzpatrick, D.M.Bozinovski, A.Héroux, P.G.Shaw, M.P.Valley, A.M.Orville.
• Ref.: Biochemistry, 2007, 46, 13800-13808.
• PubMed id: 17994768