Helix-coil transition of a polypeptide

Fig. 11. Comparison of theoretical curves, which describe the thermal helix-coil transition of a polypeptide system as a function of chain length, with experimental points obtained for poly-->-benzyl-i,-glutamate polymers of varying degrees of polymerization, n. In this solvent mixture, ethylene dichloride and dichloroacetic acid, the helical form, characterized by the more positive rotations, is stable at higher temperatures. The manner in which increased length sharpens the transition, both in theory and in actuality, is here clearly illustrated. For comparative purposes, Tc is defined as the temperature at the mid-point of the transition for the sample of highest molecular weight. (Zimm et al., 1959.)...

The helix-coil transition of a polypeptide chain consisting of N monomers is usually described in terms of two parameters ... 

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