Effects of glycerol on the compaction and stability of the wild type and mutated rabbit muscle creatine kinase

All organisms have developed detect, repair, regulation, and stabilization mechanisms to survive from cellular and molecular damage induced by diverse stresses. Among them, the accumulation of osmolytes is a common mechanism evolved by cells to maintain cell volume and stabilize macromolecules against various environmental stresses. The molecular mechanisms by which osmolytes stabilize proteins and prevent aggregation have been well-established. However, little is known about the effects of osmolytes on mutated or damaged proteins. In this research, we investigated the effects of glycerol on the activity, structure, and stability of the wild type (WT) and D54G CK under normal and extreme (high temperature) conditions. It was found that glycerol had similar effects on the suppression of the aggregation during the refolding of both proteins. Under native conditions, the effect of glycerol on the mutated protein was more obvious than on the WT protein. Glycerol could efficiently force the mutated protein to fold to a state close to the WT protein, and thus stabilize the native state of the mutated protein. Glycerol could also protect both the WT and mutated proteins against heat-induced denaturation. However, the change in the transition free energy of heat-induced inactivation of the WT protein was larger than that of the mutated protein. These results suggested that glycerol might have differential effects on the changes of the chemical potential and the transition free energy of the WT and mutated proteins.