Binding interaction between sodium carboxymethyl cellulose and serum albumin: Insights from multi-spectroscopy methods, rheological characterization and molecular docking analysis

Protein-polysaccharide interactions have attracted increasing interest due to their wide range of applications in food engineering and novel food formulations. This study provides a comprehensive analysis of the binding interaction between bovine serum albumin (BSA) and carboxymethyl cellulose (CMC), combining spectroscopic, rheological, and molecular docking approaches for the first time. The CD results showed that the α-helix content in the secondary structure of BSA increased from 33 % to 45 % with the addition of CMC. UV spectroscopy results suggested the formation of a complex between CMC and BSA. CMC quenched the fluorescence of BSA through both dynamic and static quenching mechanisms. The number of binding sites (n), Stern-Volmer constant (K_sv), and static quenching constant (K_a) were 0.36, 4.32 × 10⁵ L/mol, and 55.2 L/mol, respectively. The rheological analysis showed that the viscosity of BSA decreased with increasing concentrations of BSA, indicating a shear-thinning behavior. Molecular docking confirmed that CMC is inserted into subdomain IIA (site I) of BSA, forming two hydrogen bonds with the amino acid residues Arginine-458 and Serine-192. This study provides novel insights into BSA-CMC interactions, with implications for designing functional materials in food science and biotechnology.