Behavior of glycopolypeptides with empirical molecular weight estimation methods. 1. In sodium dodecyl sulfate

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Abstract
The influence of the presence of oligosaccharide branches was examined with respect to the behavior of glycopolypeptides in empirical MW estimation methods in the presence of sodium dodecyl sulfate [SDS]. This examination was conducted by comparing the gel chromatographic and gel electrophoretic behaviors in the presence of SDS of 13 glycopolypeptides of known chemical and physical properties to those of regular polypeptides. Errors in the gel chromatographic MW for glycopolypeptides in SDS varied from -22% to +10% and indicated that the hydrodynamic behavior of the glycopolypeptide SDS complex could not be correlated with the amount of carbohydrate in the glycopolypeptide. SDS binding measurements on a number of the glycopolypeptides suggest that the polypeptide moiety binds the nominal weight ratio of SDS, while the carbohydrate portion exhibits little or no SDS binding. As was previously reported, the polyacrylamide gel electrophoretic behavior of glycopolypeptide SDS complexes yielded abnormally high MW estimates. The error of these estimates generally diminished with decreasing porosity of the gel; each glycopolypeptide behaved in a unique fashion. Treatment of the electrophoretic data by any of several empirical means provided no reliable way to correct for the glycopolypeptides'' aberrant behavior.