PDBsum entry: 1gvo

Flavoenzyme

PDB id: 1gvo

Contents

Protein chain

362 a.a. *

Ligands

FMN

DNF

Waters ×818

* Residue conservation analysis

PDB id:

1gvo

Name:

Flavoenzyme

Title:

Stucture of pentaerythritol tetranirate reductase and complexed with 2,4 dinitrophenol

Structure:

Pentaerythritol tetranitrate reductase. Chain: a. Engineered: yes. Other_details: 2,4 dinitrophenol is bound in the active site

Source:

Enterobacter cloacae. Organism_taxid: 550. Expressed in: escherichia coli. Expression_system_taxid: 562. Other_details: ncbi u68759. Recombinant

Resolution:

1.38Å R-factor: 0.175 R-free: 0.200

Authors:

T.Barna,P.C.E.Moody

Key ref:

H.Khan et al. (2002). Kinetic and structural basis of reactivity of pentaerythritol tetranitrate reductase with NADPH, 2-cyclohexenone, nitroesters, and nitroaromatic explosives. J Biol Chem, 277, 21906-21912. PubMed id: 11923299 DOI: 10.1074/jbc.M200637200

Date:

22-Feb-02 Release date: 20-Feb-03

Protein chain

P71278  (P71278_ENTCL) -  Pentaerythritol tetranitrate reductase

Seq: 365 a.a.

Struc: 362 a.a.

 Gene Ontology (GO) functional annotation 

• Biological process: metabolic process (1 term)
• Biochemical function: catalytic activity (3 terms)

DOI no: 10.1074/jbc.M200637200

J Biol Chem 277:21906-21912 (2002)

PubMed id: 11923299

Kinetic and structural basis of reactivity of pentaerythritol tetranitrate reductase with NADPH, 2-cyclohexenone, nitroesters, and nitroaromatic explosives.

H.Khan, R.J.Harris, T.Barna, D.H.Craig, N.C.Bruce, A.W.Munro, P.C.Moody, N.S.Scrutton.

ABSTRACT

The reaction of pentaerythritol tetranitrate reductase with reducing and oxidizing substrates has been studied by stopped-flow spectrophotometry, redox potentiometry, and X-ray crystallography. We show in the reductive half-reaction of pentaerythritol tetranitrate (PETN) reductase that NADPH binds to form an enzyme-NADPH charge transfer intermediate prior to hydride transfer from the nicotinamide coenzyme to FMN. In the oxidative half-reaction, the two-electron-reduced enzyme reacts with several substrates including nitroester explosives (glycerol trinitrate and PETN), nitroaromatic explosives (trinitrotoluene (TNT) and picric acid), and alpha,beta-unsaturated carbonyl compounds (2-cyclohexenone). Oxidation of the flavin by the nitroaromatic substrate TNT is kinetically indistinguishable from formation of its hydride-Meisenheimer complex, consistent with a mechanism involving direct nucleophilic attack by hydride from the flavin N5 atom at the electron-deficient aromatic nucleus of the substrate. The crystal structures of complexes of the oxidized enzyme bound to picric acid and TNT are consistent with direct hydride transfer from the reduced flavin to nitroaromatic substrates. The mode of binding the inhibitor 2,4-dinitrophenol (2,4-DNP) is similar to that observed with picric acid and TNT. In this position, however, the aromatic nucleus is not activated for hydride transfer from the flavin N5 atom, thus accounting for the lack of reactivity with 2,4-DNP. Our work with PETN reductase establishes further a close relationship to the Old Yellow Enzyme family of proteins but at the same time highlights important differences compared with the reactivity of Old Yellow Enzyme. Our studies provide a structural and mechanistic rationale for the ability of PETN reductase to react with the nitroaromatic explosive compounds TNT and picric acid and for the inhibition of enzyme activity with 2,4-DNP.

Selected figure(s)

Figure 8.
Fig. 8. Difference electron density for each of the PETN reductase-ligand complexes. The contours are at 3 . A, the complex of oxidized enzyme and 2-cyclohexenone. B, the complex of oxidized enzyme and picric acid. C, the complex of oxidized enzyme and 2,4-DNP. D, the complex of oxidized enzyme and TNT.

Figure 9.
Fig. 9. The structure of TNT as the resonance hybrid of several canonical forms, illustrating the enhancement in the electrophilicity of C-3 and C-5 (A), and reduction of TNT to form the Meisenheimer-hydride complex (B).

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2002, 277, 21906-21912) copyright 2002.

Figures were selected by an automated process.