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.