Glycerol induced stability enhancement and conformational changes of β-lactoglobulin

Abstract The protective mechanism of glycerol on β-lactoglobulin were studied in 0-60% glycerol solutions by experimental and molecular simulation approaches. Results showed that the stability of β-lactoglobulin increased with glycerol concentration, with little secondary structure changes induced by glycerol. The tertiary structure altered slightly with glycerol concentration, resulting in a stronger near UV circular dichroism signal and intrinsic tryptophan fluorescence quenching, indicating aromatic side chains closer to hydrophobic microenvironment. The Rg of β-lactoglobulin increased with glycerol concentration without dimer dissociation, due to expansion of the quaternary structures. Moreover, the flexibility (RMSF) of β-lactoglobulin decreased by glycerol. Distance between areas enclosing Asp33 and Arg40 from separate chains did not increase, suggesting possibly reinforced electrostatic attractions. In conclusion, the stabilization of β-lactoglobulin in glycerol solution is probably the comprehensive results of the decreased molecular flexibility, the strengthened hydrophobic interaction in individual chain, and the possibly reinforced electrostatic attractions between two chains of β-lactoglobulin.