Bacillus fordii MH602海因酶序列及同源建模分析  

Analysis of the sequence and homology modeling from Bacillus fordii MH602

作　　者：季青春[1] 梅艳珍[1] 何冰芳[1] 

机构地区：[1]南京工业大学制药与生命科学学院,江苏南京210009

出　　处：《计算机与应用化学》2008年第12期1521-1525,共5页Computers and Applied Chemistry

基　　金：国家863项目(2007AA021306);国家973项目(2003CB716004)

摘　　要：海因酶是5-取代海因生物转化制备手性氨基酸的关键酶。通过同源建模法建立MH602海因酶的三维结构,经分析,91.3%的氨基酸残基在可信区间,无氨基酸残基在不可信区间,而且能量处于较低水平,此模型可进一步研究。将MH602海因酶序列和PDB数据库中现有的6个海因酶序列比较(PDB编号为:1K1D,1YNY,1NFG,1GKP,1GKQ,1GKR),结果显示了保守的活性位点残基(4个HIS,1个ASP),3个立体化学环(SGLs)和底物环外侧链结合的残基(MET63,PHE65,LEU94,PHE152,TYR155,VAL158,LEU159)。通过比较发现MH602海因酶在159位是LEU,比其他海因酶的PHE159提供更大的底物结合空间,可能降低了对映体选择性但增加了对羟基苯海因的活力。为利用定点突变改造酶分子,提高MH602菌株生产L氨基酸的能力提供理论指导。Hydantoinase is the critical enzyme that catalysis 5-substituted hydantoins to corresponding chiral amino acids. We proposed a model for Bacillus fordii MH602 hydantoinase, based on homology modeling method. The model was possible by modeling evaluation and energy analysis since that 91.3% amino acid residues are in the most favored regions and no amino acid residue is in the disallowed regions. The energy of the model and template （1YNY） are both in low level. It indicates conserved active residues （4 HIS and 1 ASP）, 3 stereochemistry gate loops （SGLs） and the residues binding the exocyclic substituent of substrate by multiple sequence alignment with 6 hydantoinases （PDB codes：lKID, 1YNY, 1NFG, 1GKP, 1GKQ, 1 GKR）. Comparing to the residue PHE159 from other hydantoinases, the corresponding residue is LEU159. It provides more space for substrate binding, so it might decrease enantioselectivity but increase activity of 5-hydroxyphenylhydantoin. It provides information to reconstruct MH602 hydantoinase for improving the production of L-amino acids.

关 键 词：海因酶 同源建模 序列 活性位点 

分 类 号：O641[理学—物理化学]