Reduction of nitrogen oxides by gamma-irradiated hemoproteins. Pt. 2. Reduction of nitrite by immobilized gamma-irradiated hemoprotein

Sodium and potassium nitrites are used for coloration and pasteurization of meat products as food additives. Recently, removal of nitrite in water has been one of the research area in environmental science because of the necessity of reducing water pollution. The horse cardiac cytochrome c in 0.1mM aqueous solution was denatured by gamma-irradiation at a dose of 10kGy in the presence of air, and was immobilized by lattice entrapment method in the polyacrylamide gel. The immobilized irradiated cytochrome c was reacted with nitrite in the presence of reducing agent (sodium hydrosulfite) and electron carrier (methyl viologen) at 30degC. The remaining nitrite was determined by diazo-reaction. Immobilized irradiated cytochrome c could be used as a substituent of nitrite reductase, and especially high nitrite reducing activity under nitrogen atmosphere in acidic range, and entrapment in 15% gel made possible to reuse denatured cytochrome c several times. (J.P.N.)