Study on bio-imprinted Aspergillus niger lipase cross-linked aggregates and catalytic synthesis of Vitamin E succinate

Abstract

To enhance the esterification and stability of lipase in organic solvents, the bio-imprinted Aspergillus niger lipase combined with cross-linked aggregate immobilization was investigated. The bio-imprinted lipase cross-linked aggregates were applied to the catalytic esterification for the synthesis of Vitamin E succinate in N, N-dimethylformamide (DMF) solution. Lauric acid, serving as a succinic acid analogue, was selected as the bio-imprinting molecule, 0.10 g lauric acid was added to 36 mL of 2.10 mg/mL lipase solution, imprinting 40 mins at pH 8.0, the immobilization yield achieved 91.5 % with cross-linked aggregates by glutaraldehyde. The catalytic activity of the bio-imprinted lipase cross-linked aggregates was significantly enhanced, achieving an esterification yield of 87.4 ± 0.43 % for Vitamin E succinate. Moreover, the bio-imprinted lipase cross-linked aggregates maintained their catalytic activity over five consecutive reaction cycles in DMF. Fluorescence spectroscopy analysis revealed that bio-imprinting promoted the exposure of the lipase active sites, which corresponded with the observed increase in esterification activity. In addition, the mechanism of the substrate analogue-imprinted lipase was characterized. This study provides a theoretical foundation for improving the catalytic esterification performance of lipase as well as a process basis for the enzymatic synthesis of Vitamin E succinate.