The thermal denaturation of bovine β-lactoglobulin B was investigated by high-sensitivity differential scanning microcalorimetry between pH 1.5 and 3.0 in 2OmM phosphate buffer. The process was found to be a reversible, two-state transition. Progressive addition of guanidine hydrochloride at pH 3.0 leads to the appearance of a low-temperature calorimetric endotherm, corresponding to the cold renaturation of the protein. Circular dichroism experiments have confirmed the low and high temperature denaturation processes, and have shown some structural differences between both denatured states of β-lactoglobulin B.
