Cyclic analog of elastin polyhexapeptide exhibits an inverse temperature transition leading to crystallization

The cyclic dodecapeptide analog of the linear polyhexapeptide of tropoelastin crystallizes from water on raising of the temperature and thereby demonstrates an inverse temperature transition implying dominant intermolecular hydrophobic interactions. The temperature profiles of turbidity (TP tau) of the cyclododecapeptide are analogous to those of the polyhexapeptide where increases in concentration lead to translations of the profiles to lower temperature without sharpening of the transition. The demonstration of increase in order with increase in temperature for the cyclododecapeptide in water and the similarity of TPtau's lends credence to the view that increases in temperature lead to increases in order, specifically, for the linear polyhexapeptide and, generally, for the precursor protein of the elastic fiber wherein the repeating hexapeptide occurs.