1as8
STRUCTURE OF NITRITE BOUND TO REDUCED ALCALIGENES FAECALIS NITRITE REDUCTASE AT CRYO TEMPERATURE
OverviewOverview
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 StructureAbout this Structure
1AS8 is a Single protein structure of sequence from Alcaligenes faecalis. Full crystallographic information is available from OCA.
ReferenceReference
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 Page seeded by OCA on Fri May 2 10:38:25 2008