Benzaldehyde lyase (BAL)-catalyzed enantioselective CC bond formation in deep-eutectic-solvents–buffer mixtures

Deep-eutectic-solvents (DES) have emerged in the last decades as promising bio-based and biodegradable neoteric solvents for biocatalysis, with examples covering different enzymes (mostly hydrolases) and whole-cells (bakerʹs yeast). This paper explores for the first time the use of benzaldehyde lyase (BAL), a thiamine-diphosphate dependent lyase (ThDP-lyase) able to catalyze the carboligation of aldehydes (CC bond formation) in different DES–buffer mixtures. By using choline chloride–glycerol DES, BAL remains fully active with excellent enantioselectivity at 60:40 DES–buffer (v/v), whereby a significant denaturation is observed at 70:30 mixtures. Remarkably, the use of choline chloride–urea DES as reaction media leads to full conversions with BAL at such solvent–buffer proportions, suggesting that the design of both the biocatalyst and the neoteric solvent may provide useful novel reactive systems for biocatalysis in non-conventional media.