Halide-stabilizing残留的卤代烷dehalogenases研究量子力学计算和定点诱变。
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Bohac M,经营着Y, Z h神,h神M, Monincova M,津田米,Koca J, Damborsky J
Halide-stabilizing残留的卤代烷dehalogenases研究量子力学计算和定点诱变。
生物化学。2002年12月3日,41 (48):14272 - 80。
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12450392 (在PubMed]
- 文摘
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卤代烷dehalogenases催化裂解carbon-halogen债券的卤代脂肪族化合物,导致形成的酒精、卤化物和质子反应产物。三种结构特点的卤代烷dehalogenases至关重要的催化性能:(i)催化三分子,(2)一个oxyanion洞,(3)halide-stabilizing残留。Halide-stabilizing残留不结构保存在不同的卤代烷dehalogenases。的水平稳定的过渡态结构S (N) 2卤化反应和离子所提供的每一个活性部位残留酶DhlA, LinB, DhaA被量子力学计算量化。明显稳定的残留卤化物离子被分配为主(基本)或二级halide-stabilizing残留物(不重要)。定点诱变与LinB酶进行确认其主要halide-stabilizing残留的位置。Asn38Asp、Asn38Glu Asn38Phe、Asn38Gln Trp109Leu, Phe151Leu, Phe151Trp, Phe151Tyr, LinB Phe169Leu突变体的构建,净化,活动特征。下面的活性位点残基被列为主要halide-stabilizing残留:Trp125和Trp175 DhlA;Asn38和Trp109 LinB;和Asn41 Trp107 DhaA。 All these residues make a hydrogen bond with the halide ion released from the substrate molecule, and their substitution results in enzymes with significantly modified catalytic properties. The following active site residues were classified as the secondary halide-stabilizing residues: Phe172, Pro223, and Val226 of DhlA; Trp207, Pro208, and Ile211 of LinB; and Phe205, Pro206, and Ile209 of DhaA. The differences in the halide stabilizing residues of three haloalkane dehalogenases are discussed in the light of molecular adaptation of these enzymes to their substrates.