Sustainable synthesis of chiral β-amino acids from renewable feedstocks is of significant importance. The Rodionov reaction is a popular method to synthesize rac-β-amino acids from aldehydes, which are abundant byproducts of biomass. rac-β-Amino acids are easily converted into the enantiopure (R)-form by kinetic resolution using (S)-β-transaminases (TAs). However, the inaccessibility of natural (R)-β-transaminases with a broader substrate scope limits the application of the Rodionov reaction to produce (S)-β-amino acids. Here, we report the kinetic resolution of rac-β-amino acids by employing fold type-IV transaminase from Thermobaculum terrenum (TATT) with natural (R)-β-transaminase activity. Various rac-β-amino acids were successfully resolved by TATT into (S)-form with excellent conversions (∼50%) and enantiomeric excess (>99%) using pyruvate as an amino acceptor. The directed evolution of TATT resulted in a variant M-58 (K112F/F114M) with ∼2-fold higher activity and was able to perform large-scale kinetic resolution of 20 mM rac-3-amino-3-(3-fluorophenyl) propanoic acid (1h) with complete conversion and enantiomeric excess >99% within 24 h.

中文翻译：

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示例 IV 型折叠转氨酶的天然 (R)-β-转氨潜力，用于动力学拆分由醛合成的 rac-β-氨基酸

从可再生原料可持续合成手性 β-氨基酸具有重要意义。 Rodionov 反应是一种从醛类合成外消旋-β-氨基酸的常用方法，醛类是生物质的丰富副产品。通过使用 ( S ) -β-转氨酶 (TA) 的动力学拆分，外消旋-β-氨基酸很容易转化为对映体纯 ( R )-形式。然而，难以获得具有更广泛底物范围的天然( R )-β-转氨酶限制了Rodionov反应生产( S )-β-氨基酸的应用。在这里，我们报告了通过使用来自Thermobaculum terrenum (TATT)的具有天然( R ) -β-转氨酶活性的折叠IV型转氨酶来动力学拆分rac -β-氨基酸。使用丙酮酸作为氨基受体，各种外消旋-β-氨基酸通过 TATT 成功解析为 ( S )-形式，具有出色的转化率 (∼50%) 和对映体过量 (>99%)。 TATT 的定向进化产生了活性高约 2 倍的变体 M-58 (K112F/F114M)，并且能够对 20 mM rac -3-氨基-3-(3-氟苯基)进行大规模动力学拆分丙酸 ( 1 小时) 在 24 小时内完全转化且对映体过量 >99%。