Dioxygenase and co-oxidase activities of rat hepatic cytosolic lipoxygenase.
The role of rat liver cytosolic lipoxygenase in the metabolism of benzidine was studied using linoleic acid as a cosubstrate. Under optimum assay conditions, cytosolic dioxygenase activity in the presence of 3.5 mM linoleic acid at pH 7.2 was 74.07 +/- 1.43 nmoles/min/mg protein. Benzidine was oxidized at the rate of 3.18 +/- 0.13 nmoles/min/mg cytosolic protein to benzidine diimine at pH 7.2 in the presence of 3.65 mM linoleic acid. Both dioxygenase and co-oxidase reactions were inhibited by nordihydroguaiaretic acid in a concentration-dependent manner. Partially purified preparations of rat liver lipoxygenase, free of hemoglobin, exhibited a dioxygenase activity of 223.1 +/- 65.9 nmoles/min/mg protein and co-oxidase activity of 6.1 +/- 0.5 nmoles/min/mg protein toward benzidine. These results suggest that hepatic lipoxygenase may play an important role in the metabolism of this hepatocarcinogen.
Roy
S K
SK
Department of Environmental and Occupational Health, College of Public Health University of South Florida, Tampa 33612.
Kulkarni
A P
AP
D000818:Animals; D001560:Benzidines / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology*; D005260:Female; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D019746:Intramolecular Oxidoreductases; D007535:Isomerases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008041:Linoleic Acids / Q000378:metabolism; D008084:Lipoxygenase / Q000378:metabolism*; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology; D008099:Liver / Q000201:enzymology*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000502:physiology; D010544:Peroxidases / Q000378:metabolism*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D013347:Subcellular Fractions / Q000201:enzymology
D001560:Benzidines; D008041:Linoleic Acids; D016859:Lipoxygenase Inhibitors; C029876:benzidine; D010544:Peroxidases; D008084:Lipoxygenase; D007535:Isomerases; D019746:Intramolecular Oxidoreductases; C021377:hydroperoxide isomerase