Membrane-associated, dissimilatory nitrite reductase of the denitrifying fungus Cylindrocarpon tonkinense

Dissimilatory nitrite reductase (Nir) of the fungus Cylindrocarpon tonkinen se was isolated and partially characterized. Nir activity was recovered in both the soluble and the membrane fractions, giving a specific activity of 4.74 and 5.80 mu mol NO min(-1) (mg protein)(-1), respectively. The soluble and membrane-associated Nir preparations resembled each other in propertie s, and the results suggested that Nir is a homodimer of a 67-kDa subunit. T he absorption spectrum and the inhibition by diethyldithiocarbamate indicat ed that fungal Nh is a copper-containing Nir (CuNir).