Inactivation of soybean lipoxygenase by lipoxygenase inhibitors in the presence of 15-hydroperoxyeicosatetraenoic acid.

Soybean lipoxygenase is rapidly inactivated when incubated with arachidonic acid and any of several lipoxygenase inhibitors, including NDGA, the aminopyrazolines BW 755C and BW 540C, and the acetohydroxamic acid derivatives BW A4C and BW A137C. Little or no inactivation was found when the enzyme was incubated with substrate or with inhibitors alone. 15-HPETE was as effective as arachidonic acid in promoting inactivation, but linoleic acid and 13-HPOD were much less effective. The UV absorption at 235 nm, due to the conjugated diene in 15-HPETE or 13-HPOD, was rapidly destroyed in the presence of soybean lipoxygenase and inhibitor in a presumed pseudoperoxidase reaction. The products of the reaction between linoleic acid, BW A137C and soybean lipoxygenase have been partially characterized. A derivative of arachidonic acid is postulated to be the inactivating agent.