pH-Tunable gliadin-chitosan-lipase ternary complexes enabling efficient interfacial synthesis of phytosterol ester

Nature employs non-catalytic scaffold proteins to achieve precise enzyme positioning and enhanced catalysis. However, mimicking this approach with food-grade macromolecular materials remains a significant challenge. Herein, we introduce a pH-tunable gliadin-chitosan matrix designed to act as a bioinspired scaffold. It spontaneously self-assembles with lipase into stable ternary complex, gliadin-chitosan-lipase (GCL), through robust hydrogen bonding and hydrophobic interactions (∆G_binding = -331.7 kJ‧mol^-1) immobilize lipase AYS in an optimally active conformation. Upon addition to an oil-water mixture at pH 7, GCL particles adsorb at the interface, creating a highly efficient Pickering interfacial biocatalysis (PIB) system. When applied to the synthesis of sterol esters via interesterification with flaxseed oil, the GCL-stabllized PIB system achieved an 81.4 % yield within 6 h, a relative conversion rate of almost three times that of free lipase (31.8 %), and maintained 73.4 % of its initial activity after five consecutive cycles. Its compatibility extended to six commercial oils. Molecular dynamics results indicated that lipase acts as a regulatory element, suppressing global fluctuations to generate stable structures with high catalytic activity, thereby preparing the interface for biocatalysis. This work establishes a sustainable, scalable platform for functional lipid production and provides a blueprint for next-generation biomacromolecular enzyme carriers.