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Intrinsic curvature of plasmid DNAs analyzed by polyacrylamide gel electrophoresis
Author(s) -
Strutz Kurt,
Stellwagen Nancy C.
Publication year - 1996
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.1150170605
Subject(s) - puc19 , plasmid , electrophoresis , gel electrophoresis , restriction enzyme , chemistry , dna , agarose gel electrophoresis , agarose , microbiology and biotechnology , biology , biophysics , genetics
The electrophoretic mobility of two small DNA plasmids, pUC19 and Litmus 28, linerarized by digestion with a variety of single‐cut restriction enzymes, has been studied. The permuted sequence isomers migrate with identical mobilities in agarose gels, as expected, but exhibit different mobilities in large‐pore polyacrylamide gels, suggesting that the parent plasmids contain sequencespecific sites of curvature and/or anisotropic flexibility. Both plasmids contain apparent bend centers near their origin(s) of replication; pUC19 also has a major apparent bend center near the promoter of the ampicillin resistance gene. These apparent bend centers are observed under a variety of experimental conditions, suggesting that they correspond to sites of stable curvature in the parent plasmids. Both plasmids also contain minor bend centers that are observed under a sub‐set of electrophoretic conditions and disappear when divalent cations are added to the solution, suggesting that these apparent bend centers may correspond to localized regions of variable flexibility.