Dynamic mechanical analysis of poly-α-amino acids. Models for collagen

Abstract

A series of copolymers of L-leucine and L-glutamic acid was prepared as a model system for collagen, and the dynamic mechanical behavior was investigated as a function of water content. The results suggest a spectrum of waterpolymer interactions with the two predominant types represented by “tightly bound” and “loosely bound” water. Each gives rise to a characteristic relaxation peak: the former at 180–200°K (1 Hz) and the latter at about 260°K (1 Hz). One of the poly-α-amino acids, a 50:50 copolymer of L-leucine and L-glutamic acid, sorbed an amount of water comparable to that of native collagen. Below physiological temperature the relaxation spectrum of this polymer closely resembles that reported for collagen in both temperature location and intensity of relaxation peaks. This suggests that the use of model polymers may be of significant value in elucidating the structure and function of water in structural proteins.