PDBsum entry 2reh

Oxidoreductase

PDB id: 2reh

Contents

Protein chains

430 a.a. *

Ligands

FAD ×4

Waters ×56

* Residue conservation analysis

PDB id:

2reh

Name:

Oxidoreductase

Title:

Mechanistic and structural analyses of the roles of arg409 and asp402 in the reaction of the flavoprotein nitroalkane oxidase

Structure:

Nitroalkane oxidase. Chain: a, b, c, d. Engineered: yes. Mutation: yes

Source:

Fusarium oxysporum. Expressed in: escherichia coli.

Resolution:

2.40Å R-factor: 0.207 R-free: 0.263

Authors:

P.F.Fitzpatrick,D.M.Bozinovski,A.Heroux,P.G.Shaw,M.P.Valley, A.M.Orville

Key ref:

P.F.Fitzpatrick et al. (2007). Mechanistic and structural analyses of the roles of Arg409 and Asp402 in the reaction of the flavoprotein nitroalkane oxidase. Biochemistry, 46, 13800-13808. PubMed id: 17994768

Date:

26-Sep-07 Release date: 03-Jun-08

Protein chains

Q8X1D8  (NAO_FUSOX) -  Nitroalkane oxidase from Fusarium oxysporum

Seq: 439 a.a.

Struc: 430 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.1.7.3.1 - nitroalkane oxidase.
• Reaction:
  1. a primary nitroalkane + O2 + H2O = an aldehyde + nitrite + H2O2 + H⁺
  2. a secondary nitroalkane + O2 + H2O = a ketone + nitrite + H2O2 + H⁺
• Cofactor: FAD

FAD (Bound ligand (Het Group name = FAD) corresponds exactly)

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

Biochemistry 46:13800-13808 (2007)

PubMed id: 17994768

Mechanistic and structural analyses of the roles of Arg409 and Asp402 in the reaction of the flavoprotein nitroalkane oxidase.

P.F.Fitzpatrick, D.M.Bozinovski, A.Héroux, P.G.Shaw, M.P.Valley, A.M.Orville.

ABSTRACT

The flavoprotein nitroalkane oxidase (NAO) catalyzes the oxidation of primary and secondary nitroalkanes to the corresponding aldehydes and ketones. The enzyme is a homologue of acyl-CoA dehydrogenase. Asp402 in NAO has been proposed to be the active site base responsible for removing the substrate proton in the first catalytic step; structurally it corresponds to the glutamate which acts as the base in medium chain acyl-CoA dehydrogenase. In the active site of NAO, the carboxylate of Asp402 forms an ionic interaction with the side chain of Arg409. The R409K enzyme has now been characterized kinetically and structurally. The mutation results in a decrease in the rate constant for proton abstraction of 100-fold. Analysis of the three-dimensional structure of the R409K enzyme, determined by X-ray crystallography to a resolution of 2.65 A, shows that the critical structural change is an increase in the distance between the carboxylate of Asp402 and the positively charged nitrogen in the side chain of the residue at position 409. The D402E mutation results in a smaller decrease in the rate constant for proton abstraction of 18-fold. The structure of the D402E enzyme, determined at 2.4 A resolution, shows that there is a smaller increase in the distance between Arg409 and the carboxylate at position 402, and the interaction of this residue with Ser276 is perturbed. These results establish the critical importance of the interaction between Asp402 and Arg409 for proton abstraction by nitroalkane oxidase.