(7R,8S)-diaminopelargonic acid transaminase from the cold-adapted Gram-negative bacterium Psychrobacter cryohalolentis (Pcryo361) is able to react with unnatural substrates including (S)-( +)-1-phenylethylamine, aldehydes and α-diketones. Additionally, Pcryo361 is active at 0–50 °C and retains up to 10% of the maximum activity at 0 °C. Here, we report a detailed study on the stability and low temperature activity of Pcryo361. At the optimal pH for (S)-amine activity (pH 10.0), the enzyme was stable at 0–10 °C and no decrease in the enzyme activity was observed within 24 h in a slightly alkaline medium, pH 8.0, at 35 °C. Pcryo361 was solvent stable and was activated in 10% DMSO and DMFA at 35 °C. An analysis of the efficiency of catalysis of Pcryo361 at 35 °C and 10 °C showed that the specificity towards (S)-( +)-1-phenylethylamine dropped at 10 °C; however, the specificity towards 2,3-butanedione remained unchanged. Inhibition analysis showed that Pcryo361 activity was not inhibited by acetophenone but inhibited by amines (products of aldehyde amination). The observed pH stability and low temperature activity of Pcryo361 with activated keto substrates are attractive features in the field of development of stereoselective amination at low temperatures.

中文翻译：

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pH和温度对冷适应细菌Psychobacter cryohalolentis中转氨酶（S）-胺活性的影响。

来自冷适应的革兰氏阴性细菌Psychobacter cryohalolentis（Pcryo361）的（7 R，8 S）-二氨基壬酸转氨酶能够与非天然底物发生反应，包括（S）-（+）-1-苯基乙胺，醛和α-二酮。此外，Pcryo361在0–50°C时有活性，并在0°C时保留最大活性的10％。在这里，我们报告对Pcryo361的稳定性和低温活性的详细研究。在（S）-胺活性的最佳pH （pH 10.0）下，该酶在0–10°C时稳定，在弱碱性介质（pH 8.0）中在35°C下24小时内未观察到酶活性的降低。 C。Pcryo361具有溶剂稳定性，并在35°C的10％DMSO和DMFA中被活化。在35°C和10°C下对Pcryo361的催化效率分析表明，对（S）-（+）-1-苯基乙胺的特异性在10°C下下降；然而，对2，3-丁二酮的特异性保持不变。抑制分析表明，Pcryo361活性不受苯乙酮抑制，但受胺（醛胺化产物）抑制。在低温下立体选择性胺化开发领域中，观察到的具有活化的酮基底物的Pcryo361的pH稳定性和低温活性是吸引人的特征。