中国科学院天津工业生物技术研究所Dunming Zhu小组近日取得一项新成果。经过不懈努力，他们揭示了l‐赤式‐3,5‐二氨基己酸脱氢酶的晶体结构和催化机理，并实现不对称合成β‐氨基酸的理性工程化。 这一研究成果于2021年2月24日发表在国际顶尖学术期刊《德国应用化学》上。

该课题组研究人员报告了l‐赤式‐3,5‐二氨基己酸脱氢酶及其变体的晶体结构，这是β-AADHs家族中唯一已知成员。晶体结构分析、定点诱变研究和量子化学计算揭示了α-AADHs在底物结合和催化机制上的差异。

然后，研究人员获得了大量理性工程化的变体，对各种脂肪族β-氨基酸的活性提高了110-800倍，且没有对映选择性的妥协。课题组使用了突出的变体，以优异的对映选择性(>99%的ee)和高的分离收率(86% - 87%)，制备了两个β -氨基酸。

这些结果为3,5-DAHDH的分子机理提供了重要的见识，并为进一步设计用于不对称合成β-氨基酸的β-AADHs奠定了坚实的基础。

据了解，氨基酸脱氢酶(AADHs)作为生物催化剂，在手性氨基酸的不对称合成中显示了相当大的潜力。然而，与广泛研究的α-AADHs相比，关于β-AADHs能够合成β-氨基酸的知识有限。

附：英文原文

Title: Crystal Structures and Catalytic Mechanism of l‐erythro‐3,5‐Diaminohexanoate Dehydrogenase and Rational Engineering for Asymmetric Synthesis of β‐Amino Acids

Author: Na Liu, Lian Wu, Jinhui Feng, Xiang Sheng, Jian Li, Xi Chen, Jianjiong Li, Weidong Liu, Jiahai Zhou, Qiaqing Wu, Dunming Zhu

Issue&Volume: 2021-02-24

Abstract: Amino acid dehydrogenases (AADHs) have shown considerable potential as biocatalysts in the asymmetric synthesis of chiral amino acids. However, compared to the widely studied α‐AADHs, limited knowledge is available about β‐AADHs that enable the synthesis of β‐amino acids. Herein we report the crystal structures of a  l  ‐  erythro  ‐3,5‐diaminohexanoate dehydrogenase and its variants, the only known member of β‐AADH family. Crystal structure analysis, site‐directed mutagenesis studies and quantum chemical calculations revealed the differences in the substrate binding and catalytic mechanism from α‐AADHs. A number of rationally engineered variants were then obtained with improved activity by 110‐800 times toward various aliphatic β‐amino acids without enantioselectivity trade‐off. Two β‐amino acids were prepared using the outstanding variants with excellent enantioselectivity (> 99%  ee  ) and high isolated yields (86%‐87%). These results provide important insights into the molecular mechanism of 3,5‐DAHDH, and establish a solid foundation for further design of β‐AADHs for the asymmetric synthesis of β‐amino acids.

DOI: 10.1002/anie.202017225

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202017225