The active site of a zinc-dependent metalloproteinase influences the computed pKa of ligands coordinated to the catalytic zinc ion
The active site of a zinc-dependent metalloproteinase influences the computed pKa of ligands coordinated to the catalytic zinc ion
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DOI：
10.1021/ja0201810
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发表时间：
2002-09-18
影响因子：
15
通讯作者：
Madison, VS
中科院分区：
文献类型：
--
作者：
Cross, JB;Duca, JS;Madison, VS
TNF-α转化酶（TACE）是一种多结构域的膜锚定蛋白，包括一个锌依赖性蛋白酶结构域。它从其膜结合前体释放可溶形式的细胞因子肿瘤坏死因子-α（TNF-α）。TACE是一种金属蛋白酶，含有催化谷氨酸Glu-406和连接到三个咪唑的Zn 2+离子。活性位点谷氨酸和抑制剂的质子化状态是理解具有酸性锌连接基团（如异羟肟酸和羧酸）的抑制剂效力的重要因素。采用密度泛函方法，使用TACE催化位点模型计算pK（a）值，并预测伴随的结合机制，与降低结合配体的pK（a）和升高活性位点Glu-406的pK（a）一致。弱酸，如异羟肟酸，以其中性形式结合，然后将酸性质子转移到Glu-406。较强的酸，如羧酸，以其阴离子形式结合，需要Glu-406的预质子化。对于其他锌依赖性蛋白酶，预期类似的结合事件。
TNF-alpha converting enzyme (TACE) is a multidomain, membrane-anchored protein that includes a Zn-dependent protease domain. It releases the soluble form of cytokine tumor necrosis factor-alpha (TNF-alpha) from its membrane-bound precursor. TACE is a metalloprotease containing a catalytic glutamic acid, Glu-406, and a Zn2+ ion ligated to three imidazoles. The protonation states of the active site glutamic acid and inhibitors are important factors in understanding the potency of inhibitors with acidic zinc-ligating groups such as hydroxamic and carboxylic acids. Density functional methods were utilized to compute pK(a) values using a model of the catalytic site of TACE and to predict a concomitant mechanism of binding, consistent with lowering the pK(a) of the bound ligand and raising the pK(a) of the active site Glu-406. Weak acids, such as hydroxamic acids, bind in their neutral form and then transfer an acidic proton to Glu-406. Stronger acids, such as carboxylic acids, bind in their anionic form and require preprotonation of Glu-406. Similar binding events would be expected for other zinc-dependent proteases.