Immobilization of porcine pancreatic lipase onto a metal-organic framework, PPL@MOF: A new platform for efficient ligand discovery from natural herbs.

In terms of ligand fishing, the amount and the relative activity recovery of enzymes immobilized on magnetic particles and nanoparticles are not preeminent. Therefore, the metal-organic framework (MOF) UiO-66-NH2 was synthesized to immobilize the porcine pancreatic lipase (PPL) via precipitation-cross-linking, and the resulting novel biological matrices named PPL@MOF manifested high PPL loading capacity (98.31 mg/g) and relative activity recovery (104.4%). Moreover, the novel enzyme-MOF composite was applied to screen lipase inhibitors from Prunella vulgaris L. to enrich and improve the techniques of ligand fishing. As a result, 13 lipase ligands were obtained, and 12 compounds were determined by HPLC-Q-TOF-MS/MS. All of these ligands were further confirmed to be potential inhibitors through the verification of the activity assay and molecular docking. The proposed approach based on PPL@MOF was superior in terms of abundant protein loading capacity, high enzyme catalytic activity and easy preparation process. Taken together, our newly developed method provided a new platform for efficient discovering bioactive molecules from natural herbs.