Purification and some properties of nitrite reductase from Clostridium perfringens

Nitrite reductase from Clostridium perfringens was purified by chromatographies on DEAE-cellulose, DEAE-Sephadex, Sephadex G-150, and hydroxylapatite and by isoelectric focussing to a homogeneous state, showing essentially a single protein band in disc gel electrophoresis and a single immuno-precipitation line in double diffusion against antiserum obtained from immunized rabbits. The reductase was induced in the presence of nitrate. It had a molecular weight of 54,000 and showed no absorption peak in the visible region. The pH optimum was 6.2 and Km for nitrite was 5 mM. Ferredoxin, as well as viologen dyes, was found to be an electron donor. The product of nitrite reduction was hydroxylamine. This reductase was inhibited by o-phenanthroline and azide but not by cyanide or diethyldithiocarbamate.