Determination of Polymer Molecular Weight and Gyration Radius of DNA by Capillary Electrophoresis

The paper is concerned with the novel method on polymer molecular weight and gyration radius of DNA (R g ) detection by a quantitative DNA sieving model using DNA separations by capillary electrophoresis, which was proposed by us previously. First, the molecular weights of polymer additives such as hydroxylpropyl cellulose (HPC) and hydroxyethyl cellulose (HEC) were calculated by the intercept of a linear plot of (1/1/0)1/2 against . The relative differences between the predicted and the actual values (M w=80, 000 to 1, 000, 000) were all within the range of 0.61% to 6.71%. Second, the radius of gyration (R g) of DNA in the collision direction of the Y-axis can be also calculated simultaneously. Results indicated that R g depends on the DNA length, polymer concentration, polymer species, and polymer M w. R g lengthens with increased DNA length, but shortens with increased solution concentration and polymer M w. Furthermore, R g of DNA was longer in linear polyacrylamide (LPA) than in HEC solution when the concentration was fixed.