Gel electrophoresis measurement of counterion condensation on DNA.
We used agarose gel electrophoresis to measure the effective charge neutralization of DNA by counterions of different structure and valence, including Na+, Mg2+, Co(NH3)3+6, and spermidine3+, which competed for binding with an excess of Tris acetate buffer. Linear DNA molecules ranged in size from 1 to 5 kilobases, and supercoiled plasmid pUC18 was also measured. In all cases, the results were in good agreement with theoretical predictions from counterion condensation theory for two-counterion mixtures.
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Department of Biochemistry, University of Minnesota, St. Paul 55108.
Bloomfield
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D002413:Cations, Divalent; D004247:DNA / Q000737:chemistry*; D004278:DNA, Superhelical / Q000737:chemistry; D004587:Electrophoresis, Agar Gel; D008962:Models, Theoretical
D002413:Cations, Divalent; D004278:DNA, Superhelical; D004247:DNA