秋茄叶缩合单宁对蘑菇酪氨酸酶的抑制机理

Abstract

[中文文摘]研究了红树植物秋茄叶缩合单宁对蘑菇酪氨酸酶单酚酶活力和二酚酶活力的影响和抑制动力学.结果表明秋茄叶缩合单宁不仅可以降低蘑菇酪氨酸酶单酚酶酶促反应的稳定态活力,也可以延长反应的迟滞时间,并具有浓度依赖关系,随着抑制剂浓度增大,稳定态活力下降,迟滞时间延长.当抑制剂质量浓度达33.00μg/mL时,稳定态活力从100%下降到74%,迟滞时间从32.7s增加到72.9s;秋茄叶缩合单宁对二酚酶的抑制也显示浓度效应,抑制效果显著,引起酶活力下降50%的抑制剂质量浓度(IC50)为30.00μg/mL,其对二酚酶的抑制显示可逆的效应,抑制类型为混合型,对游离酶的抑制常数(KI)为25.05μg/mL和对酶-底物络合物的抑制常数(KIS)为46.69μg/mL.本研究揭示了植物秋茄叶缩合单宁作为一种新型酪氨酸酶抑制剂的可能性.[英文文摘]The inhibitory mechanism of condensed tannins from the mangrove plant Kandelia candel on monophenolase and o-diphenolase activity of mushroom tyrosinase has been studied.The results show that the steady-state rate of monophenolase has been decreased and the lag time has been lengthened with the increase of concentration of condensed tannins.When the concentration of the condensed tannins came to be 33.00μg／mL,the steady-state rate of monophenolase has been decreased 26%,and the lag time has been extensed from 32.7s to 72.9s.The inhibition on o-diphenolase activity can be obviously observed.The results show that inhibitor’s concentration leading to 50% activity lost(IC50) is estimated to be 30.00μg／mL.The inhibition kinetics analyzed by linewaver-burk plots shows that condensed tannins from the mangrove plant Kandelia candel is mixed-type inhibition.The inhibition constant(KI) was determined to be 25.05μg／mL and KIS was determined to be 46.69μg／mL.Condensed tannins from the mangrove plant Kandelia candel is showed to be a potential mushroom tyrosinase inhibitor in this study.