Web Release Date: December 6,
Dynamic Cross-Linking Effect of Mg2+ To Enhance Sieving Properties of Low-Viscosity Poly(vinylpyrrolidone) Solutions for Microchip Electrophoresis of Proteins
and
Department of Applied Chemistry, Graduate School of Engineering, Venture Business Laboratory (VBL), MEXT Innovative Research Center for Preventive Medical Engineering, Plasma Nanotechnology Research Center, Nagoya University, Nagoya 464-8603, Japan, Health Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Takamatsu 761-0395, Japan, and Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585, Japan
Received for review September 20, 2007. Accepted October 16, 2007.
Abstract:
We report a dynamic cross-linking effect of Mg2+ that
enhances the sieving properties of low-viscosity poly(vinylpyrrolidone) (PVP) solutions. A low-viscosity PVP
solution was applied to nondenaturing microchip electrophoresis of protein samples using microchips made of
poly(methyl methacrylate). The separation resolution of
nondenatured protein markers in 1.8% PVP solution was
improved by adding 1-20 mM MgCl2. We studied the
effect of the ratio of cross-linking agent on mobility of
protein samples and showed that protein retardation (ln
/0) is correlated with the ratio of cross-linking agent to
PVP ([cMg2+/cPVP]) as ln /0 = A'[cMg2+ /cPVP]b'. A' was
related to the protein radius (R), and b' was found to be
0.72 for proteins with R = 2.4 nm and 0.82 for proteins
with R = 1.85 nm. A structural study of PVP in semidilute
solutions using dynamic light scattering showed that
incremental increases of Mg2+ ion concentration from 5
to 20 mM in 1.8% PVP solution increased the hydrodynamic radius of PVP polymers by 20%.
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