Purification and properties of a copper-containing nitrite reductase from a denitrifying bacterium, Alcaligenes faecalis strain S-6.

A copper-containing nitrite reductase was purified and crystallized from a potent denitrifying bacterium, Alcaligenes faecalis strain S-6. The enzyme was composed of 4 subunits with a molecular weight of about 30,000, each containing 1 atom of Cu2+. Nitric oxide was identified as a main reduction product from nitrite in the enzyme-catalyzed reaction. The enzyme activity was inhibited strongly by KCN but only slightly by sulfhydryl reagents such as p-chloromercuribenzoate and N-ethylmaleimide.