CHARACTERIZATION OF A NICOTINAMIDE ADENINE DINUCLEOTIDE SPECIFIC NITRITE REDUCTASE FROM ESCHERICHIA COLI, STRAIN K12

A nitrite reductase specific for reduced nicotinamide adenine dinucleotide (NADH) was purified approximately 30-fold from Escherichia coli, strain K12. The enzyme was metal sensitive, being inhibited by certain chelating agents and stimulated by others. The optimum pH for enzymic activity was 7.8–8.0 and the Michaelis constants for nitrite and NADH were 4.0 × 10−5 moles/l, and 3.3 × 10−4 moles/l., respectively. The partially purified enzyme did not show a flavin requirement and ammonia was not the product of the enzymic reaction.