Docking studies and model development of tea polyphenol proteasome inhibitors: Applications to rational drug design
Docking studies and model development of tea polyphenol proteasome inhibitors: Applications to rational drug design
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DOI：
10.1002/prot.10504
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发表时间：
2004-01-01
影响因子：
2.9
通讯作者：
Dou, QP
中科院分区：
文献类型：
--
作者：
Smith, DM;Daniel, KG;Dou, QP
以前，我们证明了天然和合成的含酯键的绿色茶多酚是有效的和特定的非肽类蛋白酶体抑制剂。然而，抑制的分子机制目前尚不清楚。在这里，我们报告说，（-）-表没食子儿茶素-3-没食子酸酯（EGCG）的20 S蛋白酶体的胰凝乳蛋白酶活性的抑制是时间依赖性的和不可逆的，暗示β 5-亚基的催化N-末端苏氨酸（Thr 1）的酰化。这些知识与计算机对接实验一起沿着用于帮助理解结合和抑制。在这些对接实验的基础上，我们提出，（-）-表没食子儿茶素没食子酸酯结合胰凝乳蛋白酶位点的方向和构象，这是适合于由Thr 1的亲核攻击。一致地，从（-）-EGCG的亲电羰基碳到Thr 1的羟基的距离被测量为3.18埃。此外，（-）-EGCG的A环作为酪氨酸模拟物，结合到β 5亚基的疏水S1口袋。在该过程中，（-）-EGCG易断裂键可能变得紧张，这可能降低Thr 1的羟基攻击的活化能。通过比较天然存在的、先前合成的或合理合成的几种EGCG类似物的预测和实际活性来验证该模型。蛋白质2004;54：58-70. (C)2003 Wiley-Liss，Inc.
Previously, we demonstrated that natural and synthetic ester bond-containing green tea polyphenols were potent and specific non-peptide proteasome inhibitors. However, the molecular mechanism of inhibition is currently unknown. Here, we report that inhibition of the chymotrypsin activity of the 20S proteasome by (-)-epigallocatechin-3-gallate (EGCG) is time-dependent and irreversible, implicating acylation of the beta5-subunit's catalytic N-terminal threonine (Thr 1). This knowledge is used, along with in silico docking experiments, to aid in the understanding of binding and inhibition. On the basis of these docking experiments, we propose that (-)-EGCG binds the chymo-trypsin site in an orientation and conformation that is suitable for a nucleophilic attack by Thr 1. Consistently, the distance from the electrophilic carbonyl carbon of (-)-EGCG to the hydroxyl group of Thr 1 was measured as 3.18 Angstrom. Furthermore, the A ring of (-)-EGCG acts as a tyrosine mimic, binding to the hydrophobic S1 pocket of the beta5-subunit. In the process, the (-)-EGCG scissile bond may become strained, which could lower the activation energy for attack by the hydroxyl group of Thr 1. This model is validated by comparison of predicted and actual activities of several EGCG analogs, either naturally occurring, previously synthesized, or rationally synthesized. Proteins 2004;54:58-70. (C) 2003 Wiley-Liss, Inc.