Goldreich D, Grossman S, Sofer Y, Breitbart E, Sklan D
Department of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
Int J Vitam Nutr Res. 1997;67(1):4-9.
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 microM) 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.
脂氧合酶催化多不饱和脂肪酸（如亚油酸和花生四烯酸）的双加氧反应。本研究的目的是检测视黄醇、全反式视黄酸和13-顺式视黄酸对脂氧合酶-1和脂氧合酶-2催化亚油酸活性的影响。通过测定234nm处吸光度的变化来跟踪脂氧合酶对亚油酸的活性。所有类视黄醇均抑制脂氧合酶-1和脂氧合酶-2的活性。在pH 6.5时，脂氧合酶-2对亚油酸的活性很快；全反式视黄醇（10μM）使反应速率降低50%。全反式视黄醇的氧化与脂氧合酶-2产生二烯的过程同时发生。全反式视黄醇和全反式视黄酸竞争性抑制脂氧合酶-2对亚油酸的活性；13-顺式视黄酸表现出混合型抑制作用。在pH 9.0时，视黄酸对脂氧合酶-1催化亚油酸的活性也有32%-73%的抑制作用。全反式视黄酸和13-顺式视黄酸竞争性抑制脂氧合酶-1的活性，而全反式视黄醇以混合型方式抑制脂氧合酶-1的活性。这些发现表明，类视黄醇可能与酶的活性位点结合，或同时作为抗氧化剂发挥作用。
