Cooperative Formation, Transformation, and Collapse of Hydrogen-Bonds in Polypeptides

摘要

This is one of a series of studies on the reversal of the helix sense of polyaspartates originated from the pioneering work of Goodman and his associates in 1960's. After extensive studies on poly(aspartic acid ester)s in various organic solvents, it has been concluded that these polymers may be in either the right- or left-handed helical form with suitable condition of solvent and temperature. Reversal of the helix sense in binary copolymers including two different characters were found to follow a S-shape curve. Around the mid point of the transition, the magnitude of the optical rotation as well as the Moffitt-Yang b_0 changes somewhat steeply. The stereochemical structure of copolymers in this region has been investigated in relation to the mechanism of the helix-sense inversion of polyaspartates.