Contribution of translational and rotational entropy to the unfolding of a dimeric coiled-coil

The influence of translational and rotational entropy in the unfolding of a dimeric coiled-coil has been investigated in aqueous solution. To this end, the calorimetrically measured unfolding entropies of a synthetic two-stranded alpha-helical coiled-coil with and without a disulfide bond between the two polypeptide chains were compared to determine the entropy of intersubunit cross-linking of a compound. The resultant translational and rotational entropy was found to be more than an order of magnitude smaller than estimates based on ideal gas statistics.