Electrophoresis in Polymer Solutions:  Mechanisms of Molecular Sieving

Abstract

Passsage of rigid, "spherical" proteins in the range of 2-5 nm radius, R (40-500 kDa molecular weight), through semidilute solutions of a representative polymer, polyethylene glycol in the molecular weight range of (0.6-8) × 10 6 , gives rise to a size dependent retardation ("molecular sieving") analogous to that in a porous network composed of random planes. The average distance between those planes being equal to the screening length, , the retardation can be described by log(µ/µ 0 ) ) -(ARc 0.75 ) where A is a constant dependent on solvent and type of monomer and c is the polymer concentration.

Capillary zone electrophoresis of proteins in semidilute polymer solutions: Inter- and intra-polymer predictability of size-dependent retardation

“…In fact, the Ferguson plots corresponding to different concentration regions (well above the relevant c*), characterized by a progressive shift toward higher concentrations with a decrease in PEG molecular weight, were combined. This appeared to be justified since the molecular weight dependence of retardation in the semidilute concentration regime at a given polymer concentration was found to be slight [ln(m/m o )~M r 0.04 ] [18,19].…”

“…1 (also see Table 1). However, PEG is the only polymer commercially available in a great variety of molecular weights over a large range, from less than 10 5 to 10 7 , thus rendering the approach employed earlier [18,19] inapplicable to other kinds of polymers.…”

“…Earlier, it was demonstrated [18,19] that the relative electrophoretic mobility of proteins in the size range of 2.4± 5 nm radius (60±500 kDa), measured by CZE in semidilute solutions of polyethylene glycol (PEG) of various molecular weights, is related to polymer concentration as…”

Capillary Gel Electrophoretic Analysis of Cattle Breeds Based on Difference of DNA Mobility of Microsatellite Markers

“…There are pores within these gels and, as the charged solutes migrate through the gel-filled capillary, they are separated by a molecular sieving mechanism on the basis of their sizes. 27 Firstly, we investigated the molecular sieving mechanism using a gel polymer with a single molecular weight. However, we could not obtain good separation results (data not shown).…”

Size-dependent retardation and resolution by electrophoresis of rigid, submicron-sized particles, using buffered solutions in presence of polymers: A review of recent work from the authors' laboratory

“…These properties are: (i) a concave plot of the logarithm of relative mobility, m/m o , vs. polymer concentration (Ferguson plot), at least in PA and PEG solutions, which can be linearized by plotting the 0.75th power of the polymer concentration (Figs. 2 of [6] and [7]) with the resulting slope designated as retardation coefficient, K R ; (ii) a linear plot with positive slope of K R vs. particle radius (ªR-plotº; ]) and near-independence of the molecular weight of the polymer (Fig. 1 of [6]); (iv) availability of at least four different theoretical treatments which account for the retardation in the terms of a fit of the particle into the available spacings of the polymer network [9±11] or in terms of hydrodynamic interactions [12].…”