Determination of the base composition of deoxyribonucleic acid from its buoyant density in CsCl

Carl L. Schildkraut, Julius Marmur, Paul Doty

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739 Scopus citations


A comprehensive study of the buoyant density of DNA as a function of composition has been made. The linear relation previously reported has been confirmed. Based on a value of 1·710 g cm−3 for DNA from Escherichia coli the following relation was obtained from the best fit of measurements on 51 different DNA samples: ρ=1⋅660+0⋅098(GC) where ρ refers to buoyant density and (GC) to the mole fraction of guanine plus cytosine. On this basis the composition of DNA from 36 other sources, not previously reported, has been estimated. Several specific observations were made. Bimodal distributions in the density-gradient band patterns were found in DNA from calf thymus and salmon sperm. The DNA of the commonly studied T-even bacteriophages exhibits altered densities due to the presence of gluco-sylated hydroxymethylcytosine. The DNA of φX174 phage is abnormally heavier suggesting less base-pairing than normal denatured, single-stranded DNA.

Original languageEnglish (US)
Pages (from-to)430-443
Number of pages14
JournalJournal of Molecular Biology
Issue number6
StatePublished - 1962
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Biophysics
  • Structural Biology


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