Use of capillary electrophoresis for the determination of the conformation and size of individual components in a biopolymer distribution: 1. Theory and application to amylose and dextran

Derivatized low DP (degree of polymerization) oligomers of the polysaccharides amylose and dextran have been separated in aqueous solution at low pH using capillary electrophoresis and a novel model of polymer migration has been used to determine chain characteristics. The model is based on Debye-Huckel-Henry theory and a treatment of the polymers as simple freely rotating chains. Our results show that in the limit of zero ionic strength electrophoretic mobility is proportional to the inverse square root of the degree of polymerization, supporting the belief that amylose and dextran are random coils in aqueous solution. The characteristic ratio of amylose was found to be 3.2 using our model. Dextran chains were shown from electrophoretic mobilities to be more extended than amylose chains of equivalent degrees of polymerization, in agreement with results obtained from gel permeation chromatography.