Arginine-rich hemp seed globulin-tannic acid non-covalent complexation: Structural compaction, enhanced antioxidant/emulsifying properties, and modulated digestibility.

Abstract

This study elucidates the non-covalent interaction mechanism between hemp seed globulin (GLB), a plant protein rich in arginine, and tannic acid (TA) via combined multispectral analysis and molecular simulations. TA adopts an amphipathic binding mode within a defined GLB pocket, driven mainly by hydrophobic forces and supplemented by hydrogen bonds and arginine-mediated cation-π interactions, which collectively drive an entropy-favorable spontaneous binding process (ΔH > 0, ΔS > 0). TA binding drives localized secondary structural adjustments and enhances conformational compactness of GLB. The resulting GLB-TA complex exhibits significantly improved antioxidant activity and emulsifying properties, alongside reduced in vitro digestibility. This work elucidates a specific interaction paradigm between high-arginine plant globulins and hydrolysable polyphenols, providing a mechanistic basis for clean-label plant protein modification and supporting sustainable functional food development, aligned with UN SDGs 3 (Good Health and Well-being) and 12 (Responsible Consumption and Production).