Reduction of aryl-nitroso compounds by pyridine and flavin coenzymes.
1. A systematic kinetic investigation of the reduction of aryl-nitroso compounds by pyridine and flavin coenzymes and their analogs, in enzymatic and nonenzymatic systems, has been reported. 2. Two main groups of nitroso compounds have been investigated, representatives nitroso-benzene and 1-nitroso-2-naphthol; in all enzymatic and nonenzymatic systems, the former was always reduced to phenyl-hydroxyl-amine and the latter to 1-amino-2-naphthol. 3. Pyridine compounds included NADH, APAD-4H2 and DBNA-4H2 in nonenzymatic systems, and liver alcohol dehydrogenase. Flavin compounds included 1,5-dihydrolumiflavin and various forms of reduced 5-ethyl-lumiflavin, in nonenzymatic systems, and the flavoenzymes glucose-oxidase and NADPH-cytochrome P450 reductase. 5. Pyridine coenzymes and their analogs reduced nitroso compounds by a direct hydride transfer, with a primary kinetic isotope of 9.5 +/- 2.2. 6. All flavin compounds (glucose-oxidase and its nonenzymatic analog 1,5-dihydrolumiflavin and NADPH-cytochrome P450 reductase and its analog 5-ethyl-1,5-dihydrolumiflavin) reduced aryl-nitroso compounds with high efficiency (k2 greater than 10(5)M(-1) min(-1)). 7. The flavin compounds have been shown to be much more efficient reductans of nitroso compounds, compared to pyridine coenzymes, both in enzymatic and nonenzymatic systems; the only exception to this rule presented the extremely efficient reduction of p-substituted aryl-nitroso compounds by liver alcohol dehydrogenase.
Leskovac
V
V
Faculty of Technology, Novi Sad, Yugoslavia.
Svircević
J
J
Trivić
S
S
Popović
M
M
Radulović
M
M
D000693:Anaerobiosis; D003067:Coenzymes / Q000378:metabolism*; D005415:Flavins / Q000378:metabolism*; D007700:Kinetics; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism; D009536:Niacinamide / Q000031:analogs & derivatives / Q000378:metabolism; D009603:Nitroso Compounds / Q000378:metabolism*; D010084:Oxidation-Reduction; D011725:Pyridines / Q000378:metabolism*; D013053:Spectrophotometry
D003067:Coenzymes; D005415:Flavins; D009603:Nitroso Compounds; D011725:Pyridines; D009536:Niacinamide; D009251:NADPH-Ferrihemoprotein Reductase