2007 Volume 17 Issue 1 Pages 13-22
By using spectroscopies under high pressure, we determined the volume changes associated with protein folding of reduced cytochrome c from the unfolded state to the native state. The pressure dependence of the equilibrium constant for the denaturation and the folding rate revealed that the volume change for the protein folding and the activation volume for the native state are negative. Such negative volumes can be accounted for by a decrease in volume resulting from the dehydration of hydrophobic groups, primarily the heme group, and the dehydration is mainly induced in the formation of the transition for the native state. We, therefore, propose that dehydration can compensate for the decreased entropy in the formation of protein structures, entropically promoting the protein folding reactions.
