Copper-containing nitrite reductase isolated from Hyphomicrobium sp. A
3151 has been characterized by electronic absorption, circular dichro
ism (CD) and electron paramagnetic resonance (EPR) spectroscopies. The
visible absorption spectrum of Type I copper (blue copper) in the enz
yme especially indicates novel features compared with those of Type I
coppers in not only several nitrite reductases already reported but al
so small blue copper proteins. The EPR spectrum of Type I copper exhib
its an axial symmetry.