CONFORMATIONAL-ANALYSIS OF ALPHA,BETA-POLY(N-HYDROXYETHYL)-DL-ASPARTAMIDE (PHEA) AND ALPHA,BETA-POLYASPARTHYDRAZIDE (PAHY) POLYMERS IN AQUEOUS-SOLUTION

alpha,beta-Poly(N-hydroxyethyl)-DL-aspartamide (PHEA) and alpha,beta-p olyasparthydrazide (PAHy) are synthetic polymers previously studied fo r biomedical applications. We report here the results of a small-angle X-ray scattering analysis carried out on these two macromolecules in aqueous solution. The data obtained indicate that the two polymers ass ume remarkably different conformations in aqueous solution, although t he backbone is supposed to be the same for the two chains. PHEA can be represented by a random coil conformation, whereas PAHy can be descri bed in terms of an elliptical cylinder characterized by an almost plan ar structural arrangement with the backbone refolded on itself in a fa shion somewhat similar to the beta layer of globular proteins. This mo re rigid conformation of PAHy is related both to the network. of hydro gen bonds capable of stabilizing the overall structure and to the lowe r molecular weight with respect to PHEA. Conformational and energetic analyses of PAHy are also discussed. (C) 1998 Elsevier Science Ltd. Al l rights reserved.