Synthesis and application of nanoscale ZIF-67 for enhanced phospholipase A1 immobilization and high phospholipid-DHA conversion

Abstract

Phospholipid-DHA (PL-DHA) is a highly bioavailable form of docosahexaenoic acid (DHA), with enzymatic catalysis being its most promising preparation method. However, challenges such as low enzyme loading and poor catalytic efficiency restrain industrial applications. In this study, a nanoscale zeolitic imidazolate framework-67 (ZIF-67) was synthesized as a novel carrier for immobilizing phospholipase A1 (PLA1). ZIF-67 exhibited a high surface area of 1044.3 m²/g and an enzyme loading capacity of 619.80 mg/g. PLA1 immobilized on ZIF-67 displayed remarkable performance, retaining 130 % of the catalytic activity of the free enzyme under optimized conditions, highlighting its enhanced stability and reusability. ZIF-67@PLA1 demonstrated excellent catalytic performance in phospholipid esterification with unsaturated fatty acids, achieving DHA and DPA incorporation rates of 51.04 % and 10.56 %, respectively. Molecular docking revealed that PLA1 binds to ZIF-67 through hydrophobic interactions and hydrogen bonds. This study provides an efficient method for DHA/DPA-enriched phospholipid production and advances ZIF-based enzyme immobilization.

Keywords: Biocatalysis; Enzyme immobilization; Phospholipase A1; Phospholipid-DHA; ZIF-67.