Abstract:

After being subjected to wet heat treatment or treatment with different pH solutions, metal complexing agents or sulfhydryl agents, winged beans were defatted with petroleum ether, vacuum dried, powdered and soaked in 0.01 mL/L, pH 7.0 PBS solution with gentle stirring to extract lipoxygenase (Lox) into the supernatant. The enzyme solutions obtained were comparatively measured for their Lox enzyme activity to probe the effects of different treatments on the stability of Lox in winged beans. The Lox from winged beans treated with pH 8－9 solutions had the highest relative enzyme activity, suggesting that this enzyme is stable in this pH range, whereas pH values below 3 could dramatically inactivate it. Also, the enzyme was greatly inactivated by 90 ℃ heat treatment. Pairwise combined uses of sulfhydryl agents (L-cysteine and thioglycol) with metal complexing agents (citric acid, EDTA and tartaric acid) gave better inactivating effect on the enzyme as compared to their sole uses.

Key words: winged bean, Lipoxygenase, activity, inhibition