Molecular mechanisms controlling the rate and specificity of catechol O-methylation by human soluble catechol O-methyltransferase
Molecular mechanisms controlling the rate and specificity of catechol O-methylation by human soluble catechol O-methyltransferase
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DOI：
10.1124/mol.59.2.393
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发表时间：
2001-02-01
影响因子：
3.6
通讯作者：
Taskinen, J
中科院分区：
文献类型：
--
作者：
Lautala, P;Ulmanen, I;Taskinen, J
通过结合酶动力学测量、底物性质的计算建模和在酶活性位点的3D模型中拟合配体，研究了确定儿茶酚O-甲基化的周转率和特异性的分子机制。利用重组人可溶性儿茶酚O-甲基转移酶（COMT）对46种化合物进行了酶动力学测定，其中包括临床上常用的儿茶酚类药物。取代基的吸电子效应是降低转换速率和提高亲和力的重要机制。取代基影响反应性和亲和力的其他几种机制被确定。最高的周转率被确定为未取代的邻苯二酚和连苯三酚。邻苯三酚衍生物一般似乎是比儿茶酚更具体的底物。儿茶酚雌激素是最具特异性的内源性底物，而儿茶酚胺是相当差的底物。在用于L-DOPA治疗帕金森氏病的儿茶酚药物中，COMT抑制剂恩他卡朋和托卡朋未被甲基化，而DOPA脱羧酶抑制剂苄丝肼是比L-DOPA（COMT抑制的靶标）高15倍的特异性底物。发现的结构-活性关系允许预测的反应性，亲和力和特异性与有用的准确性，儿茶酚具有广泛的结构和性能。这些知识可用于评价内源性儿茶酚、药物和膳食儿茶酚的代谢相互作用，以及设计具有儿茶酚药效团的药物。
Molecular mechanisms determining the turn-over rate and specificity of catechol O-methylation were studied by combining enzyme kinetic measurements, computational modeling of substrate properties and fitting ligands in a 3D model of the active site of the enzyme. Enzyme kinetic measurements were carried out for 46 compounds, including most clinically used catechol drugs, by using recombinant human soluble catechol O-methyltransferase (COMT). The most important mechanism decreasing the turnover rate and increasing affinity was the electron withdrawing effect of substituents. Several other mechanisms by which substituents affected reactivity and affinity were identified. Highest turnover rates were determined for unsubstituted catechol and pyrogallol. Pyrogallol derivatives generally seemed to be more specific substrates than catechols. Catecholestrogens were the most specific endogenous substrates, whereas catecholamines were rather poor substrates. Among the catechol drugs used in the L-DOPA treatment of Parkinson's disease, the COMT inhibitors entacapone and tolcapone were not methylated, whereas the DOPA decarboxylase inhibitor benserazide was 15 times more specific substrate than L-DOPA, the target of COMT inhibition. The structure-activity relationships found allow the prediction of reactivity, affinity, and specificity with useful accuracy for catechols with a wide range of structures and properties. The knowledge can be used in the evaluation of metabolic interactions of endogenous catechols, drugs and dietary catechols, and in the designing of drugs with the catechol pharmacophore.