Non-enzymatic reduction of aliphatic tertiary amine N-oxides mediated by the haem moiety of cytochrome P450

Xenobiotica; the Fate of Foreign Compounds in Biological Systems
K TakekawaS Ohta

Abstract

1. The mechanism of reduction of aliphatic tertiary amine N-oxides to tertiary amines in liver microsomes was examined and a novel type of reduction by cytochrome P450 was found. 2. Rat liver microsomes exhibited a significant N-oxide reductase activity toward brucine N-oxide and imipramine N-oxide in the presence of both NAD(P)H and FAD under anaerobic conditions. These N-oxide reductase activities were inhibited by carbon monoxide or air. However, the activities were not abolished by boiling the microsomes; indeed, in the case of brucine N-oxide, the activity was enhanced. 3. The activity toward brucine N-oxide was also observed after the conversion of cytochrome P450 to cytochrome P420. Cytochrome P4502B1 alone exhibited the reductase activity in the presence of both NAD(P)H and FAD. After the removal of haem from cytochrome P4502B1, the activity was observed in the haem moiety, but not in the cytochrome P450 apoprotein. 4. Photochemically reduced FAD was effective in the reduction in place of NAD(P)H and FAD. 5. The N-oxide reduction appears to proceed non-enzymatically, catalysed by the haem group of cytochrome P450 in the presence of a reduced flavin.

References

Sep 7, 1976·Biochemical and Biophysical Research Communications·R KatoH Noguchi
Aug 22, 1977·Biochemical and Biophysical Research Communications·K IwasakiR Sato
Jun 1, 1967·European Journal of Biochemistry·Y Imai, R Sato
Apr 30, 1984·Biochemical and Biophysical Research Communications·S Kitamura, K Tatsumi
Jun 29, 1984·Biochemical and Biophysical Research Communications·S Kitamura, K Tatsumi

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Citations

Jan 5, 2002·Xenobiotica; the Fate of Foreign Compounds in Biological Systems·K TakekawaS Ohta
Nov 24, 2004·Drug Metabolism Reviews·Ursula Breyer-Pfaff
Feb 24, 2007·Toxicology and Applied Pharmacology·Adrian C NicolescuThomas E Massey
Jul 13, 2011·Xenobiotica; the Fate of Foreign Compounds in Biological Systems·Ming ZhengYiqun Deng
Jul 2, 2015·ACS Chemical Neuroscience·Cornelia HainerNatalia Alenina
Nov 28, 2017·Nature Communications·Hailey J KnoxJefferson Chan
Jun 6, 2018·Frontiers in Pharmacology·Feng LiDebananda Pati

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