Engineered hydrophobic pocket of (<i>S</i>)-selective arylmalonate decarboxylase variant by simultaneous saturation mutagenesis to improve catalytic performance
作者:Shosuke Yoshida、Junichi Enoki、Robert Kourist、Kenji Miyamoto
DOI:10.1080/09168451.2015.1060844
日期:2015.12.2
mutagenesis with a restricted set of amino acids at each position was applied to further heighten the activity of the (S)-selective AMDase variant toward α-methyl-α-phenylmalonate. The best variant (V43I/G74C/A125P/V156L/M159L/C188G) showed 9,500-fold greater catalytic efficiency kcat/Km than that of G74C/C188S. Notably, a high level of decarboxylation of α-(4-isobutylphenyl)-α-methylmalonate by the
细菌芳基丙二酸酯脱羧酶(AMDase)催化非天然芳基丙二酸酯的不对称脱羧,从而产生光学纯的(R)-芳基羧酸酯,而无需添加辅助因子。以前,我们设计了显示完全反向对映选择性的AMDase变体G74C / C188S。但是,与野生型AMDase相比,该变体的活性降低了20,000倍。进一步的研究表明,针对G74C / C188S疏水口袋中活性位点残基的迭代饱和诱变可显着提高活性,其中所有阳性变异都仅具有疏水取代作用。在这项研究中,同时在每个位置使用一组受限的氨基酸进行饱和诱变,以进一步提高(S)选择性AMDase变体对α-甲基-α-苯基丙二酸酯的活性。最佳变体(V43I / G74C / A125P / V156L / M159L / C188G)的催化效率kcat / Km比G74C / C188S高9,500倍。值得注意的是,六聚体变体使α-(4-异丁基苯基)-α-甲基丙二酸酯的高脱羧度产生