中文摘要：

[目的]分析川芎咖啡酸-3-O甲基转移酶（Caffeic acid-3-Omethyltransferase,COMT）序列特征、蛋白结构和活性位点。[方法]以紫花苜蓿中COMT的晶体结构为模板,利用同源建模构建川芎（Ligusticum chuanxiong Hort）COMT的三维模型。[结果]经过动力学优化后,川芎COMT的三维模型与紫花苜蓿COMT的结构极为相似,主要由α-螺旋和β-折叠构成,其中α-螺旋占37.26%、β-折叠占10.41%、无规卷曲占52.33%。川芎COMT含有两个重要的结构域：咖啡酸结合域与S-腺苷甲硫氨酸结合域,主要通过氢键与范德华力结合,其中咖啡酸与川芎COMT分子中的Asp208和Gly210形成氢键,S-腺苷甲硫氨酸与川芎COMT分子中的Ser186、Thr213、Ala215、Thr216、Trp268及Asp272等残基形成氢键。[结论]该文得到川芎COMT的序列特征、蛋白结构和活性位点,为该类COMT的催化机理研究和分子工程改造奠定基础。

英文摘要：

[Objective] To study the sequence signature,protein structure and active site of caffeic acid-3-O methyltransferase（COMT） from Ligusticum chuanxiong Hort.[Methods]A three dimensional model of COMT from L.Chuanxiong Hort was constructed by homology modeling using the crystal structure of CHS from Medicago sativa as a temple.[Results]Three dimensional structure of COMT from L.Chuanxiong,which was mainly composed of α-helices and some β-sheets,was similar to that of COMT from M.Sativa.After validation,the stereochemistry and internal consistency of the COMT model were reasonable.COMT model had two individual domains：one was responsible for the binding of caffeic acid and another one took charge of the binding of S-adenosyl methionine.The binding between COMT model and ligands depended on mainly hydrogen bonds and van der Waals interactions,two amino acid residues produced hydrogen bonding effect with caffeic acid,namely 208 Asp and 210 Gly,S-adenosylmethionine combined with receptor protein by hydrogen bonding interactions are 186 Ser,213Thr,215 Ala,216Thr,268 Trp,272Asp.[Conclusion]The sequence signature,protein structure and active site of COMT was discovered,which would lay a foundation of the catalytic mechanism and molecular re for ming.