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Abstract
Amine transaminases (ATAs) are biocatalysts for the synthesis of chiral amines and can be identified in sequence databases by specific sequence motifs. This study shows that the activity level towards the model substrate 1‐phenylethylamine can be predicted solely from the sequence. To demonstrate this, 15 putative ATAs with a different distribution of hydrophobic or hydrophilic amino acid side chains near the active site were characterized. Hydrophobic side chains were associated with a high activity level and were a better predictor of activity than global sequence identity to known ATAs with high or low activities. Enzyme stability investigations revealed that four out of the 15 ATAs showed a good operational stability.
Abstract
A device for the transaminase‐catalysed synthesis combined with continuous recovery of chiral amines was designed. The system enabled the separation of the reaction components in three liquid phases: a reaction phase, an organic solvent phase (where the poorly water soluble ketone substrate was supplied), and an aqueous extraction phase for continuous product recovery. The transaminase‐mediated asymmetric synthesis of (S)‐1‐methyl‐3‐phenylpropylamine was employed as model reaction. Factors influencing the performance of the system, such as reactor geometry, working volumes and operating parameters, were investigated. Specifically, reaction yield and product recovery were enhanced by i) reducing the thickness of the reaction phase, while continuously stirring and ii) reducing the volume of the extraction phase. Under the optimal condition tested, 85 % of the product formed was extracted and a product concentration value of 9 g/L was reached. However, co‐extraction of the unreacted amine donor (17 %) was observed. Advantages and drawbacks of this process compared to existing technologies, as well as possible optimization strategies are discussed.