Synthesis of β-Branched Tryptophan Analogues Using an Engineered Subunit of Tryptophan Synthase
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- 作者：Michael Herger ; Paul van Roye ; David K. Romney ; Sabine Brinkmann-Chen ; Andrew R. Buller ; Frances H. Arnold
- 刊名：Journal of the American Chemical Society
- 出版年：2016
- 出版时间：July 13, 2016
- 年：2016
- 卷：138
- 期：27
- 页码：8388-8391
- 全文大小：284K
- 年卷期：0
- ISSN：1520-5126
文摘
We report that <span class="smallcaps">lspan>-threonine may substitute for <span class="smallcaps">lspan>-serine in the β-substitution reaction of an engineered subunit of tryptophan synthase from Pyrococcus furiosus, yielding (2S,3S)-β-methyltryptophan (β-MeTrp) in a single step. The trace activity of the wild-type β-subunit on this substrate was enhanced more than 1000-fold by directed evolution. Structural and spectroscopic data indicate that this increase is correlated with stabilization of the electrophilic aminoacrylate intermediate. The engineered biocatalyst also reacts with a variety of indole analogues and thiophenol for diastereoselective C–C, C–N, and C–S bond-forming reactions. This new activity circumvents the 3-enzyme pathway that produces β-MeTrp in nature and offers a simple and expandable route to preparing derivatives of this valuable building block.