1hj4

From Proteopedia

Revision as of 14:31, 5 November 2007

CYTOCHROME CD1 NITRITE REDUCTASE, X-RAY REDUCED DIOXYGEN COMPLEX

Overview

Reduction of dioxygen to water is a key process in aerobic life, but, atomic details of this reaction have been elusive because of difficulties, in observing active oxygen intermediates by crystallography. Cytochrome, cd(1) is a bifunctional enzyme, capable of catalyzing the one-electron, reduction of nitrite to nitric oxide, and the four-electron reduction of, dioxygen to water. The latter is a cytochrome oxidase reaction. Here we, describe the structure of an active dioxygen species in the enzyme, captured by cryo-trapping. The productive binding mode of dioxygen in the, active site is very similar to that of nitrite and suggests that the, catalytic mechanisms of oxygen reduction and nitrite reduction are closely, related. This finding has implications to the understanding of the, evolution of oxygen-reducing enzymes. Comparison of the dioxygen complex, to complexes of cytochrome cd(1) with stable diatomic ligands shows that, nitric oxide and cyanide bind in a similar bent conformation to the iron, as dioxygen whereas carbon monoxide forms a linear complex. The, significance of these differences is discussed.

About this Structure

1HJ4 is a Single protein structure of sequence from Paracoccus pantotrophus with SO4, HEC, DHE and GOL as ligands. Structure known Active Sites: C1A, C1B, D1A and D1B. Full crystallographic information is available from OCA.

Reference

Structure of the bound dioxygen species in the cytochrome oxidase reaction of cytochrome cd1 nitrite reductase., Sjogren T, Hajdu J, J Biol Chem. 2001 Apr 20;276(16):13072-6. Epub 2001 Jan 26. PMID:11278884

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