Microcalorimetric studies of the heats of solution of bovine myelin basic protein

Heats of solution for myelin basic protein have been determined using microcalorimetry. All aqueous systems studied yielded negative heats of solution; in contrast, trifluoroethanol produced a small positive heat of solution, while reaction with dimethyl sulfoxide was strikingly exothermic. The heat of interaction for native myelin basic protein with 8 M urea at pH 4.0, 29 degrees C, was found to be -79 +/- 16 kcal/mol. The significance of these results in terms of the protein's structural organization is discussed.