Abstract
Nitro-reducing systems of rat liver were studied. 1. Rat liver possessed at least two different nitro-reducing systems ; they were distinguished from each other by requirement of hydrogen donor, intracellular localization and sensitivity for phenobarbital induction. 2. Microsomal reduced nicotinamide-adenine dinucleotide phosphate-linked nitro-reducing system was obtained in soluble form by the treatment of microsomes with steapsin, and was partially purified. Some properties of the solubilized system were studied. 3. Evidence was presented that microsomal NADPH-cytochrome c reductase was included in microsomal nitro-reducing system. However, the nitro-reducing system required cofactors. One of them might be flavin mononucleotide interacting weakly with protein. Effect of flavins to the nitro-reducing system was kinetically discussed.
