Polymer and Materials Science
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
The kinetic curves of the helix-refolding of (PPG)n (n = 10, 12, and 15) were analyzed with an all-or-none model. The Arrhenius plot of the overall rate constant of the helixfolding kF showed a negative activation energy at high temperature. With the aid of a sequential model, it was concluded that the reason for the anomaly was the instability of short helices (shorter than seven helical units in a trimeric molecule), and/or the more rapid rates of helix-folding and helix-opening for shorter helices.The rate constant of the formation of one helical unit composed of three tripeptides at an end of a long helix was calculated to be 102-4 sec-1. It was much smaller than that for other kinds of helices, such as an α helix (1010 sec-1) or a double helix of nucleic acids (107-9sec-1).
Type of Medium: