Behavior of glycopolypeptides with empirical molecular weight estimation methods. 2. In random coil producing solvents

Abstract

The effect of oligosaccharide branch chains on the hydrodynamic behavior of reduced glycopolypeptides was examined by gel chromatography in random coil producing solvents. This entailed a comparison of the gel chromatographic behavior in the presence of concentrated guanidinium chloride of 16 glycopolypeptides of known physical and chemical properties to that of regular polypeptides. For most glycopolypeptides employed, the presence of oligosaccharide branches sufficiently perturbed the dimensions of the unfolded glycopolypeptide such that its effective hydrodynamic radius was the same as that of a linear polypeptide of the same total mass. Gel chromatography in random coil producing solvents appears to be the most reliable empirical method to obtain a 1st approximation of the MW of a glycopolypeptide. Glycopolypeptides rich in N-acetylneuraminic acid and possessing low isoionic points exhibited more pronounced deviations in electrophoretic behavior in the presence of 8 M urea than those glycopolypeptides whose ionic properties were similar to those of the polypeptide standards employed.