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Measuring the translational diffusion coefficients of small DNA molecules by capillary electrophoresis
Author(s) -
Stellwagen Nancy C.,
Magnusdottir Soffia,
Gelfi Cecilia,
Righetti Pier Giorgio
Publication year - 2001
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/1097-0282(20010405)58:4<390::aid-bip1015>3.0.co;2-k
Subject(s) - chemistry , diffusion , capillary electrophoresis , oligomer , dna , oligonucleotide , electrophoresis , molecule , base pair , analytical chemistry (journal) , capillary action , ionic strength , ionic bonding , chromatography , thermodynamics , polymer chemistry , organic chemistry , biochemistry , ion , aqueous solution , physics
The apparent translational diffusion coefficients of four 20 base pair (bp) DNA oligonucleotides with different sequences have been measured by capillary electrophoresis, using the stopped migration method. The diffusion coefficients of the four oligomers were equal within experimental error, and averaged (120 ± 10) × 10 −8 cm 2 s −1 in 40 m M Tris–acetate–EDTA buffer at 25°C. Since this value is nearly identical to the translational diffusion coefficient determined for a different 20‐bp oligomer using other methods, the stopped migration method can accurately measure the diffusion coefficients of small DNA oligomers. The apparent diffusion coefficient of a 118‐bp DNA restriction fragment was also measured by the stopped migration method. However, the observed value was ∼25% larger than expected from other measurements, possibly because the diffusion coefficients of larger DNA molecules are somewhat dependent on the ionic strength of the solution. © 2001 John Wiley & Sons, Inc. Biopolymers 58: 390–397, 2001