Dioxygenase and Co-oxidase activities of rat hepatic cytosolic lipoxygenase

✍ Scribed by Roy, Sandip K. ;Kulkarni, Arun P.

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 830 KB
• Volume: 9
• Category: Article
• ISSN: 0887-2082
• DOI: 10.1002/jbt.2570090402

✦ Synopsis

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 r 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 cooxidase activity of 6.1 f 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.