Mutation of Cysteine-295 to Alanine in Secondary Alcohol Dehydrogenase from Thermoanaerobacter ethanolicus Affects the Enantioselectivity and Substrate Specificity of Ketone Reductions
作者:Christian Heiss、Maris Laivenieks、J.Gregory Zeikus、Robert S Phillips
DOI:10.1016/s0968-0896(01)00073-6
日期:2001.7
The mutation of Cys-295 to alanine in Thermoanaerobacter ethanolicus secondary alcohol dehydrogenase (SADH) was performed to give C295A SADH, on the basis of molecular modeling studies utilizing the X-ray crystal structure coordinates of the highly homologous T. brockii secondary alcohol dehydrogenase (1YKF.PDB). This mutant SADH has activity for 2-propanol comparable to wild-type SADH. However, the
在利用高度同源的布氏螺旋体仲醇脱氢酶(X射线晶体结构坐标)进行的分子建模研究的基础上,进行了乙醇热厌氧乙醇仲醇脱氢酶(SADH)中Cys-295突变为丙氨酸,得到C295A SADH。 1YKF.PDB)。该突变体SADH具有与野生型SADH相当的2-丙醇活性。然而,发现在一些乙炔基酮还原为相应的手性炔丙醇中,C295A突变引起对映选择性向(S)-构型的明显转变。该结果证实了我们的预测,即Cys-295是小的烷基结合袋的一部分,其大小决定了酮底物的结合方向,因此决定了产物醇的立体化学构型。此外,与野生型SADH相比,C295A SADH对叔丁基和某些α支化酮的活性高得多。C295A突变不影响SADH的硫酯还原酶活性。C295A SADH具有更广泛的底物特异性和改变的立体选择性,使其成为非对称还原的潜在有用工具。