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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 a key enzyme in the preparation of chiral amino acids by 5-substituted hydantoin bioconversion. Through the homology modeling method to establish the MH602 three-dimensional structure of the enzyme, according to the analysis, 91.3% of the amino acid residues in the confidence interval, no amino acid residues in the confidence interval, and the energy at a low level, this model can be further studied . The results showed that the conserved active site residue (4) was compared with the existing six heroinase sequences in the PDB database (PDK numbers: 1K1D, 1YNY, 1NFG, 1GKP, 1GKQ, 1GKR) One HIS, one ASP), three stereochemical loops (SGLs), and the residue (MET63, PHE65, LEU94, PHE152, TYR155, VAL158, LEU159) By comparison, MH602 heroinase is LEU at position 159, providing greater substrate binding space than other hydantoins, PHE159, may reduce enantioselectivity but increase the activity of p-hydroxybenzene. It provides a theoretical guidance for the use of site-directed mutagenesis to modify enzyme molecules and improve the ability of MH602 strains to produce L-amino acids.