Highly efficient and stereoselective biosynthesis of (2S,5S)-hexanediol with a dehydrogenase from Saccharomyces cerevisiae
作者:Marion Müller、Michael Katzberg、Martin Bertau、Werner Hummel
DOI:10.1039/b920869k
日期:——
The enantiopure (2S,5S)-hexanediol serves as a versatile building block for the production of various fine chemicals and pharmaceuticals. For industrial and commercial scale, the diol is currently obtained through bakers’ yeast-mediated reduction of 2,5-hexanedione. However, this process suffers from its insufficient space-time yield of about 4 g L−1 d−1 (2S,5S)-hexanediol. Thus, a new synthesis route is required that allows for higher volumetric productivity. For this reason, the enzyme which is responsible for 2,5-hexanedione reduction in bakers’ yeast was identified after purification to homogeneity and subsequent MALDI-TOF mass spectroscopy analysis. As a result, the dehydrogenase Gre2p was shown to be responsible for the majority of the diketone reduction, by comparison to a Gre2p deletion strain lacking activity towards 2,5-hexanedione. Bioreduction using the recombinant enzyme afforded the (2S,5S)-hexanediol with >99% conversion yield and in >99.9% de and ee. Moreover, the diol was obtained with an unsurpassed high volumetric productivity of 70 g L−1 d−1 (2S,5S)-hexanediol. Michaelis–Menten kinetic studies have shown that Gre2p is capable of catalysing both the reduction of 2,5-hexanedione as well as the oxidation of (2S,5S)-hexanediol, but the catalytic efficiency of the reduction is three times higher. Furthermore, the enzyme's ability to reduce other keto-compounds, including further diketones, was studied, revealing that the application can be extended to α-diketones and aldehydes.
高光学纯度(2S,5S)-己二醇作为一种多用途的构建单元,可用于生产各种精细化学品和药物。在工业和商业规模上,目前通过面包酵母介导的2,5-己二酮还原反应制备该二醇。然而,这一过程存在空间时间产率不足的问题,约为每天每升4克(2S,5S)-己二醇。因此,需要开发一种新的合成路线,以实现更高的体积生产率。为此,通过纯化至均一性并随后进行MALDI-TOF质谱分析,鉴定了面包酵母中负责2,5-己二酮还原的酶。结果显示,与缺乏对2,5-己二酮活性的Gre2p缺失株相比,脱氢酶Gre2p主要负责该二酮的还原。利用重组酶进行生物还原,可获得转化率>99%且对映体过量>99.9%的(2S,5S)-己二醇。此外,该二醇的体积生产率达到了前所未有的70 g L−1 d−1 (2S,5S)-己二醇。米氏动力学研究表明,Gre2p能够催化2,5-己二酮的还原和(2S,5S)-己二醇的氧化,但还原的催化效率高出三倍。此外,研究了该酶对其他酮类化合物(包括更多的二酮)的还原能力,发现其应用可扩展到α-二酮和醛。