1aq8

From Proteopedia

Revision as of 13:45, 5 November 2007

STRUCTURE OF ALCALIGENES FAECALIS NITRITE REDUCTASE REDUCED WITH ASCORBATE

Overview

The structures of oxidized, reduced, nitrite-soaked oxidized and, nitrite-soaked reduced nitrite reductase from Alcaligenes faecalis have, been determined at 1.8-2.0 A resolution using data collected at -160, degrees C. The active site at cryogenic temperature, as at room, temperature, contains a tetrahedral type II copper site liganded by three, histidines and a water molecule. The solvent site is empty when crystals, are reduced with ascorbate. A fully occupied oxygen-coordinate nitrite, occupies the solvent site in crystals soaked in nitrite. Ascorbate-reduced, crystals soaked in a glycerol-methanol solution and nitrite at -40 degrees, C remain colorless at -160 degrees C but turn amber-brown when warmed, suggesting that NO is released. Nitrite is found at one-half occupancy., Five new solvent sites in the oxidized nitrite bound form exhibit defined, but different occupancies in the other three forms. These results support, a previously proposed mechanism by which nitrite is bound primarily by a, single oxygen atom that is protonable, and after reduction and cleavage of, that N-O bond, NO is released leaving the oxygen atom bound to the Cu site, as hydroxide or water.

About this Structure

1AQ8 is a Single protein structure of sequence from Alcaligenes faecalis with CU as ligand. Active as Transferred entry: 1.7.2.1, with EC number 1.7.99.3 Structure known Active Sites: CU1, CU3 and CU5. Full crystallographic information is available from OCA.

Reference

Structure of nitrite bound to copper-containing nitrite reductase from Alcaligenes faecalis. Mechanistic implications., Murphy ME, Turley S, Adman ET, J Biol Chem. 1997 Nov 7;272(45):28455-60. PMID:9353305

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