Glycosylation of bovine serum albumin via Maillard reaction prevents epigallocatechin-3-gallate-induced protein aggregation

Polyphenols normally have strong binding affinity with proteins which often leads to precipitation. Glycosylation of protein via Maillard reaction in mild conditions may inhibit the precipitation and thus is beneficial for the development of controlled-releasable bioactive materials. In this paper, we employed fluorescence spectroscopy, small-angle x-ray scattering (SAXS), and dynamic light scattering to study the influence of the protein glycosylation on the epigallocatechin-3-gallate (EGCG) induced interaction and aggregation behaviors of bovine serum albumin (BSA). Two dextran molecules with molecular weights of 10kDa (DT10) and 20kDa (DT20) were used for protein glycosylation. The protein-dextran conjugates were found to have a core-shell structure, with BSA core radius of 4.2nm and the dextran surrounding layer thickness of 2.9nm and 2.4nm, respectively. In the presence of EGCG, large-scale aggregation was ultimately suppressed in the mixture of BSA-dextran conjugate and EGCG, in contrast to the mixture of BSA and EGCG when the dextran conjugate layer was introduced. The hydrophilic layer of dextran inhibited the interaction between BSA and EGCG which was dominated by hydrophobic interaction and/or hydrogen bonding, which has also been verified by the much lower binding affinity of EGCG with BSA-dextran conjugates than with the native protein (i.e., BSA). This work clearly shows that the glycosylation does not have any positive effect of aggregation of BSA when change the molar ratio of EGCG to protein in 100-200 times, which will be promising for polyphenol based nano-carriers development.