Dispersion coefficients of a protein and DNA fragment in polyacrylamide gel electrophoresis as a function of parameters defining the effective gel pore size and particle size

The dispersion coefficient, D ′, of the representative homogeneous protein, conalbumin, decreases linearly as the polyacrylamide concentration increases from 4 to 14%T (2%C), and varies in a biphasic fashion as %C (Bis) is increased from 2 to 20%, with a broad peak between 5 and 15%C. D ′ increases linearly with the concentration of the initiator, potassium persulfate, in the range of 0.01–0.15%. D ′ remains constant when the field strength is varied from 5 to 15 V/cm. A DNA fragment (1857 bp) exhibits a constant D ′ in 4–6% polyacrylamide (2%C) at a field strength of 1 V/cm, and a linearly increasing D ′ at 5 V/cm, in analogy to its previously observed behavior in agarose gels. In solutions of uncrosslinked polyacrylamide, the decrease of the D ′ of conalbumin with polymer concentration is not significantly different from that in 2% N,N ′‐methylenebisacrylamide‐crosslinked gels in the range of 4–14%T, while the decrease of mobility with polyacrylamide concentration is much steeper in 2% crosslinked compared to uncrosslinked polymer. Finally, –∂ (log D ′)/∂ T was found to be proportional to the retardation coefficient, K R (= –∂ (log μ)/∂ T ), in polyacrylamide gels. The ratio of –∂ (log D ′)/∂ T over K R increases with field strength in the range of 5–15 V/cm.