Phenylalanine dehydrogenases (PDHs) play an important role in pharmaceutical and fine chemical industries due to their ability to produce primary amines via asymmetrically reductive amination. However, the industrial application of PDHs are often limited by their undesirable stability, narrow substrate specificity, especially for unnatural substrates. Here, a novel PDH from Quasibacillus thermotolerans (QtPDH) was identified by gene mining using BbPDH from Bacillus badius as a probe. QtPDH exhibits prominent thermal stability, specifically a half-life of 23 days at 30 °C and pH 8.5, about 300 times longer than that of BbPDH. QtPDH could catalyze various phenylpyruvate analogues, including ethyl 2-oxo-4-phenylbutyrate and l-phenylglycinol, as well as bulky 3-(naphthalen-1-yl)-2-oxopropanoic acid with a reductive amination specific activity of 1.90 U·mg^–1. Catalyzed by QtPDH in couple with BmGDH, efficient production of 2‑chloro-l-phenylalanine was achieved at 1.0 M 3-(2-chlorophenyl)-2-oxopropionic acid with > 99 % conversion, 99 % ee, and space-time yield of 30.46 g·L^–1·h^–1. Our results suggest that this newly identified QtPDH features high catalytic efficiency and thermostability, and is a promising biocatalyst for the industrial productions of bulky aromatic primary amines.

苯丙氨酸脱氢酶（PDH）由于能够通过不对称还原胺化产生伯胺，因此在制药和精细化工行业中发挥着重要作用。然而，PDH 的工业应用往往因其稳定性差、底物特异性窄（尤其是对于非天然底物）而受到限制。在这里，使用来自芽孢杆菌的Bb PDH作为探针，通过基因挖掘鉴定了来自耐热准芽孢杆菌( Qt PDH)的新型 PDH 。Qt PDH 表现出出色的热稳定性，特别是在 30 °C、pH 8.5 下的半衰期为 23 天，比Bb PDH 长约 300 倍。Qt PDH可以催化各种苯基丙酮酸类似物，包括2-氧代-4-苯基丁酸乙酯和l-苯基甘氨醇，以及大体积的3-(萘-1-基)-2-氧代丙酸，还原胺化比活性为1.90 U·毫克^–1。在Qt PDH与Bm GDH 的共同催化下，在 1.0 M 3-(2-氯苯基)-2-氧代丙酸下实现了2-氯-l-苯丙氨酸的高效生产，转化率 > 99 %， ee 99 % ，空间-一次收率30.46 g·L ^–1 ·h ^–1。我们的结果表明，这种新鉴定的Qt PDH 具有高催化效率和热稳定性，是大体积芳香伯胺工业生产的一种有前途的生物催化剂。