Dynamic cross-linking effect of Mg2+ to enhance sieving properties of low-viscosity poly(vinylpyrrolidone) solutions for microchip electrophoresis of proteins.
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 micro/micro0) is correlated with the ratio of cross-linking agent to PVP ([cMg2+/cPVP]) as ln micro/micro0=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%.
Department of Applied Chemistry, Graduate School of Engineering, Venture Business Laboratory (VBL), MEXT Innovative Research Center for Preventive Medical Engineering, Nagoya University, Nagoya 464-8603, Japan. rezam@mail.apchem.nagoya-u.ac.jp
Mohamad Reza
MR
Mohamadi
Noritada
N
Kaji
Manabu
M
Tokeshi
Yoshinobu
Y
Baba
D002256:Carbonic Anhydrases / Q000737:chemistry; D003432:Cross-Linking Reagents / Q000737:chemistry*; D046209:Electrophoresis, Microchip / Q000379:methods*; D024202:Electrophoretic Mobility Shift Assay; D005087:Glucan 1,4-alpha-Glucosidase / Q000737:chemistry; D006801:Humans; D007768:Lactalbumin / Q000737:chemistry; D015636:Magnesium Chloride / Q000737:chemistry*; D011205:Povidone / Q000737:chemistry*; D011489:Protein Denaturation; D011506:Proteins / Q000737:chemistry* / Q000302:isolation & purification*; D012709:Serum Albumin / Q000737:chemistry; D012996:Solutions; D014361:Trypsin Inhibitors / Q000737:chemistry; D014783:Viscosity
D003432:Cross-Linking Reagents; D011506:Proteins; D012709:Serum Albumin; D012996:Solutions; D014361:Trypsin Inhibitors; D015636:Magnesium Chloride; D007768:Lactalbumin; D005087:Glucan 1,4-alpha-Glucosidase; D002256:Carbonic Anhydrases; D011205:Povidone