Abstract In this study, an efficient enzymatic process for the synthesis of 4-hydroxyphenylacetaldehyde (4-HPAA) from tyramine was developed using whole cells of recombinant Escherichia coli co-expressing primary amine oxidase (PrAO) from E. coli and catalase (CAT) from Bacillus pumilus. The reaction conditions for the synthesis of 4-HPAA were systematically optimized starting from a monophasic aqueous buffer. The optimum reaction temperature, pH, and biocatalyst loading were 33 °C, 7.5, and 20 g/L wet cells, respectively. Substrate feeding strategies were employed to alleviate substrate inhibition, providing a 14.8 % increase in yield. A biphasic catalytic system was explored to avoid product inhibition and thus further improve the 4-HPAA yield. Ethyl acetate was found to be the best organic solvent, and the optimum volume ratio of the organic phase to the aqueous phase was 40 % (v/v). Under the optimized conditions on a 1 L scale, a yield of 76.5 % was obtained with a substrate concentration of 120 mM. Thus, the bioconversion was more efficient in the ethyl acetate/buffer biphasic system than in the monophasic aqueous system, and the yield of 4-HPAA was improved 1.89-fold.

中文翻译：

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用重组伯胺氧化酶氧化酪胺的氨基来酶促生产 4-羟基苯乙醛

摘要 在本研究中，使用共表达大肠杆菌伯胺氧化酶 (PrAO) 和过氧化氢酶 (CAT) 的重组大肠杆菌全细胞开发了一种从酪胺合成 4-羟基苯乙醛 (4-HPAA) 的有效酶促工艺。来自短小芽孢杆菌。从单相水性缓冲液开始，系统地优化了合成 4-HPAA 的反应条件。最佳反应温度、pH 值和生物催化剂负载量分别为 33 °C、7.5 和 20 g/L 湿细胞。采用底物补料策略来减轻底物抑制，使产量增加 14.8%。探索了双相催化系统以避免产物抑制，从而进一步提高 4-HPAA 的产率。发现乙酸乙酯是最好的有机溶剂，有机相与水相的最佳体积比为40%（v/v）。在 1 L 规模的优化条件下，以 120 mM 的底物浓度获得了 76.5% 的产率。因此，乙酸乙酯/缓冲液双相体系中的生物转化比单相水体系中的生物转化效率更高，4-HPAA 的产率提高了 1.89 倍。