Bioinspired artificial lipase with engineered hydrophilic microenvironment for oriented substrate binding and...

Lipases are pivotal biocatalysts for the tailored synthesis of structured lipids, owing to their capacity for precise triglyceride modification. Natural lipases contain an independent substrate-binding domain, termed the lid region, that regulates substrate selectivity and establishes a hydrophilic microenvironment for selective binding to the glycerol backbone of triglycerides. Drawing inspiration from this mechanism, this study has designed and constructed a series of biomimetic metal-organic frameworks with graded hydrophilicity to act as artificial lipases. Systematic investigations revealed a significant positive correlation between the hydrophilicity of artificial lipases and their oriented binding preference for the glycerol backbone (the polar head) of triglyceride molecules over the hydrophobic fatty acid alkyl chains, thereby successfully mimicking the substrate recognition mechanism of natural lipases. Of these, the hydrophilic artificial lipases exhibited the highest glycerol hydrophilic end-oriented binding, applied to the acidolysis of camellia oil for structured lipid synthesis. The artificial lipase demonstrated superior catalytic efficiency, achieving a total capric acid incorporation of 29.09%, which significantly exceeded that of the natural lipase. Furthermore, it exhibited pronounced regioselectivity, with capric acid incorporation of 41.33% at the sn-1,3 positions, in stark contrast to only 4.62% at the sn-2 position. This high sn-1,3 regioselectivity, coupled with superior overall activity, validates the efficiency and advantage of the hydrophilic microenvironment biomimetic strategy in synthesizing rapidly digestible, low-accumulating sn-1,3-specific medium- and long-chain triglycerides.