The effect of retinol and retinoic acids on lipoxygenase activity
1997
Goldreich, D. | Grossman, S. | Sofer, Y. | Breitbart, E. | Sklan, D.
Lipoxygenase catalyzes the dioxygenation of polyenoic fatty acids such as linoleate and arachidonate. The aim of the present study was to examine the effect of retinol, all-trans-retinoic acid and 13-cis-retinoic acid on the activity of lipoxygenase-1 and lipoxygenase-2 towards linoleic acid. Lipoxygenase activity toward linoleic acid was followed by determining changes in absorption at 234 nm. All retinoids inhibited lipoxygenase-1 and lipoxygenase-2 activity. Lipoxygenase-2 activity towards linoleic acid was rapid at pH 6.5; all-trans-retinol (10 micromolar) caused a 50% inhibition in reaction rate. All-trans-retinol was oxidized in parallel with diene production by lipoxygenase-2. Lipoxygenase-2 activity on linoleic acid was competitively inhibited by all-trans-retinol and all-trans-retinoic acid; 13-cis-retinoic acid exhibited mixed type inhibition. Activity of lipoxygenase-1 towards linoleic acid at pH 9.0 was also inhibited by retinoic acids by 32-73%. All-trans-retinoic acid and 13-cis-retinoic acid inhibited lipoxygenase-1 activity competitively, whereas all-trans-retinol inhibited lipoxygenase-1 activity in a mixed manner. These findings suggest that retinoids may bind to the active site of the enzyme or simultaneously act as an antioxidant.
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