Do orientation effects contribute to the molecular weight dependence of the free solution mobility of DNA?

Nancy C. Stellwagen, Alessandra Bossi, Cecilia Gelfi, Pier Giorgio Righetti

Research output: Contribution to journalArticlepeer-review

Abstract

The free solution mobility of DNA increases with increasing molecular weight and then levels off and becomes constant at molecular weights above ∼ 400 bp (Stellwagen, N. C., Gelfi, C., Righetti, P.G., Biopolymers 1997, 42, 687-703). To investigate whether the increase in mobility could be attributed to an increased orientation of the larger DNA molecules in the electric field, the free solution mobility of DNA was measured by capillary electrophoresis as a function of electric field strength. Mixtures containing 20-, 118- and 422-bp DNA molecules, and 20-, 422- and 2116-bp DNAs, were studied. If the larger DNA molecules in each mixture were oriented by the electric field, their mobilities should increase with electric field strength faster than the mobility of the 20-bp oligomer, which is too small to be oriented by the electric fields used in this study. Instead, the ratios of the mobilities of the 118-, 422- and 2116-bp fragments to the mobility of the 20-bp oligomer were independent of electric field strength. Hence, orientation effects are not important for DNA molecules up to 2 kbp in size, in electric fields up to 500 V/cm in amplitude. An explanation is suggested.

Original languageEnglish
Pages (from-to)4311-4315
Number of pages5
JournalElectrophoresis
Volume22
Issue number20
DOIs
Publication statusPublished - 2001

Keywords

  • Capillary electrophoresis
  • DNA
  • Free solution mobility
  • Orientation

ASJC Scopus subject areas

  • Clinical Biochemistry

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