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Electrophoretic mobility of linear and star‐branched DNA in semidilute polymer solutions
Author(s) -
Saha Sourav,
Heuer Daniel M.,
Archer Lynden A.
Publication year - 2006
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200500836
Subject(s) - dispersity , electrophoresis , star (game theory) , dna , electric field , chemistry , context (archaeology) , gel electrophoresis , polymer , stars , analytical chemistry (journal) , physics , astrophysics , chromatography , biology , polymer chemistry , biochemistry , paleontology , organic chemistry , quantum mechanics
Electrophoresis of large linear T2 (162 kbp) and 3‐arm star‐branched ( N Arm = 48.5 kbp) DNA in linear polyacrylamide (LPA) solutions above the overlap concentration c * has been investigated using a fluorescence visualization technique that allows both the conformation and mobility μ of the DNA to be determined. LPA solutions of moderate polydispersity index (PI ∼ 1.7–2.1) and variable polymer molecular weight M w (0.59–2.05 MDa) are used as the sieving media. In unentangled semidilute solutions ( c *< c < c e ), we find that the conformational dynamics of linear and star‐branched DNA in electric fields are strikingly different; the former migrating in predominantly U‐ or I‐shaped conformations, depending on electric field strength E , and the latter migrating in a squid‐like profile with the star‐arms outstretched in the direction opposite to E and dragging the branch point through the sieving medium. Despite these visual differences, μ for linear and star‐branched DNA of comparable size are found to be nearly identical in semidilute, unentangled LPA solutions. For LPA concentrations above the entanglement threshold ( c > c e ), the conformation of migrating linear and star‐shaped DNA manifest only subtle changes from their unentangled solution features, but μ for the stars decreases strongly with increasing LPA concentration and molecular weight, while μ for linear DNA becomes nearly independent of c and M w . These findings are discussed in the context of current theories for electrophoresis of large polyelectrolytes.