title: Characterization of nitrite reductase from a denitrifier, Alcaligenes sp. NCIB 11015. A novel copper protein.
abstract: A copper-containing dissimilatory nitrite reductase [nitric-oxide: ferricytochrome c oxidoreductase, EC 1.7.2.1] was purified from a denitrifier, Alcaligenes sp. NCIB 11015, by ion-exchange chromatography on CM-cellulose, gel filtration on Sephadex G-150, and adsorption on hydroxyapatite. The preparation was homogeneous by SDS-polyacrylamide gel electrophoretic criteria, and its enzymatic activity increased considerably by freezing (at -20 degrees C) and thawing. The enzyme consists of two subunits with a molecular weight of 37,000, and the isoelectric point and redox potential are 8.4 and +260 mV (pH 7.2), respectively. The EPR spectrum and copper analysis clearly indicated that the enzyme contains two type I copper atoms per molecule but no other types of copper. This is the first blue copper protein that exhibits catalytic activity despite possessing only type I copper.
mesh_terms: D000421:Alcaligenes / Q000201:enzymology*; D002241:Carbohydrates / Q000032:analysis; D002942:Circular Dichroism; D003300:Copper / Q000032:analysis; D007700:Kinetics; D008970:Molecular Weight; D009247:NADH, NADPH Oxidoreductases / Q000302:isolation & purification*; D009572:Nitrite Reductases / Q000302:isolation & purification* / Q000378:metabolism; D010084:Oxidation-Reduction; D011487:Protein Conformation; D013054:Spectrophotometry, Atomic
chemical_list: D002241:Carbohydrates; D003300:Copper; D009247:NADH, NADPH Oxidoreductases; D009572:Nitrite Reductases