Influence of High Pressure on Bovine Serum Albumin and Its Complex with Dextran Sulfate

Abstract

High-pressure processing of bovine serum albumin (BSA) solutions (0.1−1 wt % protein, pH 7) has shown decreasing protein surface hydrophobicity with increasing pressure, which is further reduced in the presence of dextran sulfate (DS) (BSA:DS weight ratio of 2:1 and 4:1). The total calorimetric enthalpy ΔH for pure BSA is substantially reduced after treatment at 600 MPa, and both the endothermic peak temperature and the value of ΔH for BSA + DS is reduced under the same treatment conditions. Size exclusion chromatography indicates extensive pressure-induced protein unfolding and aggregation during BSA treatment at 400 MPa. Complexation with polysaccharide at low ionic strength protects the globular protein against pressure-induced aggregation. The loss of the protective effect of DS on addition of electrolyte (0.1 M NaCl) is consistent with the predominantly electrostatic character of the protein−polysaccharide interaction. Keywords: Protein−polysaccharide interaction; high-pressure processing; surface hydrophobicity; protein aggregation; differential scanning calorimetry; size exclusion chromatography