Glycation of bovine serum albumin with monosaccharides inhibits heat-induced protein aggregation

Abstract

Glycation with different degree might result in different influence on heat-induced protein aggregation. Effects of glycation on heat-induced bovine serum albumin (BSA) aggregation was investigated, and the glycation degree was investigated. Glycation of BSA was carried out with xylose (Xyl) and galactose (Gal) via Maillard reaction at 60 °C and pH 9 for 1 and 3 days. The BSA band change was determined by SDS-PAGE, and their shape and size were then monitored by TEM and DLS. The molecule number of Xyl or Gal conjugated with BSA was determined by MALDI-TOF MS. Denaturation temperature was determined by DSC. Results show that high-molecular-weight substance and insoluble aggregates appeared when BSA was heated, while those changes were alleviated after glycation. Heat-induced changes in shape of BSA from spheroid particles to rod-like short chains, while the glycated BSA kept as spheroid particles. The size of BSA was increased by 115.7% and 204.3% after 1- and 3-day heating, respectively. The sizes of glycated BSAs were smaller than that of heated BSAs by about 37% for 1 day heating and by about 46% for 3-day heating, respectively. About 5 and 10 molecules of Xyl and about 2 and 4 molecules of Gal were conjugated with BSA after 1- and 3-day heating, respectively. The denaturation temperature of glycated BSA was higher than non-treated BSA and heated BSA. There was no obvious difference between Xyl and Gal on the inhibition effect of aggregation. In conclusion, glycation could hinder the heat-induced BSA aggregation. The higher glycation degree, the more hindrance.