Medium effects of polysaccharides: bidirectional regulation of invertase activity by sodium alginate and fenugreek gum

Sodium alginate enhanced invertase activity, whereas fenugreek gum suppressed it. Further investigation into the physicochemical properties of the medium revealed a bidirectional regulatory mechanism. Sodium alginate, characterized by a positive logarithm of the crowding factor (ln Γ), a smaller excluded volume (Vₑₓ), and improved hydration, interacted with invertase via enthalpy-driven hydrogen bonding. This interaction stabilized the α-helix and β-sheet structures of the enzyme, thereby increasing its activity. In contrast, fenugreek gum exhibited a negative ln Γ, a larger excluded volume, and lower hydration capacity. It perturbed the enzyme through entropy-driven hydrophobic interactions, leading to a reduction in β-sheet content and a consequent decrease in enzymatic activity. The overall influence of the medium—comprising viscosity, macromolecular crowding, and soft interactions—enables quantitative assessment of how polysaccharides affect invertase activity. This study offers valuable insights for the rational selection of polysaccharides in dietary formulations aimed at modulating digestive enzyme activity.