Molecular Recognition at the Active Site of Catechol-O-Methyltransferase: Energetically Favorable Replacement of a Water Molecule Imported by a Bisubstrate Inhibitor
Molecular Recognition at the Active Site of Catechol-O-Methyltransferase: Energetically Favorable Replacement of a Water Molecule Imported by a Bisubstrate Inhibitor
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DOI：
10.1002/anie.200904410
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发表时间：
2009-01-01
影响因子：
16.6
通讯作者：
Diederich, Francois
中科院分区：
文献类型：
--
作者：
Ellermann, Manuel;Jakob-Roetne, Roland;Diederich, Francois
生物活性儿茶酚，如左旋多巴和神经递质多巴胺，通过甲基化失活。该反应在S-腺苷甲硫氨酸（SAM）和Mg 2+离子存在下由儿茶酚-O-甲基转移酶（COMT）催化。[1]COMT的小的基于硝基儿茶酚的抑制剂通过阻断所施用的l-多巴的不需要的甲基化，从而提高脑中的多巴胺水平而在帕金森病的治疗中得到应用。[2，3]最近的研究指出了COMT抑制在其他中枢神经系统疾病中的其他治疗应用，如精神分裂症[4]和抑郁症。[5]We已经开发了一系列有效的COMT双底物抑制剂，它们对儿茶酚和SAM结合位点都具有竞争性。[6]基于配体1的X射线晶体结构（IC 50 = 9 nm）[7a]与COMT和Mg 2+离子（PDB代码：1 JR 4）的三元复合物[8]，我们开始详细探索酶整个活性位点的分子识别特性。[9]重要的是，我们发现，潜在的肝毒性硝基，这是强制性的儿茶酚为基础的单底物抑制剂，不需要高亲和力的双底物抑制。[10]我们用适当的亲脂性残基取代了1的5位硝基，例如2中的4-氟苯基环（IC 50 = 31 nm），[7]并发现保持了高的竞争性抑制效力。计算机模拟研究表明，新引入的亲脂性残基占据了酶表面附近的疏水裂缝。[11]这一初步建议在这里通过X射线晶体学实验验证。
Biologically active catechols, such as l-DOPA and the neurotransmitter dopamine, are inactivated by methylation. This reaction is catalyzed by the enzyme catechol-O-methyltransferase (COMT) in the presence of S-adenosylmethionine (SAM) and Mg2+ ions.[1] Small nitrocatechol-based inhibitors of COMT find application in the treatment of Parkinson disease by blocking unwanted methylation of the administered l-DOPA, thereby enhancing dopamine levels in the brain.[2, 3] Recent studies have pointed towards additional therapeutic applications of COMT inhibition in other disorders of the central nervous system, such as schizophrenia [4] and depression.[5]We have developed a series of potent bisubstrate inhibitors for COMT which are competitive for both the catechol and the SAM binding sites.[6] Based on the X-ray crystal structure of ligand 1 (IC50= 9 nm)[7a] in a ternary complex with COMT and a Mg2+ ion (PDB code: 1JR4),[8] we started a detailed exploration of the molecular recognition properties of the entire active site of the enzyme.[9] Importantly, we found that potentially hepatotoxic nitro groups, which are mandatory in catechol-based monosubstrate inhibitors, are not required for high-affinity bisubstrate inhibition.[10] We substituted the nitro group in position 5 of 1 with appropriate lipophilic residues, such as the 4-fluorophenyl ring in 2 (IC50= 31 nm),[7] and found that the high, competitive inhibitory potency was maintained. Computer modeling studies suggested that the newly introduced lipophilic residue occupies a hydrophobic cleft near the surface of the enzyme.[11] This initial proposal is validated here experimentally by X-ray crystallography.