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Effect of temperature on the buoyant density of bacterial and viral DNA in CsCl solutions in the ultracentrifuge
Author(s) -
Vinograd Jerome,
Greenwald Robert,
Hearst John E.
Publication year - 1965
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/bip.360030201
Subject(s) - chemistry , ultracentrifuge , buoyant density , thermal expansion , dna , guanine , thermodynamics , cytosine , analytical chemistry (journal) , chromatography , nucleotide , biochemistry , physics , gene
The effect of temperature on the buoyant density of CsDNA in CsCl at equilibrium in the ultracentrifuge has been measured between 5 and 60°C. The temperature coefficients of the byoyant density for three DNA's of varying guanine‐cytosine (G‐C) contents were, within experimental error, +4.2 ± 0.3 × 10 −4 g./ml.°C. This coefficient may be used to normalize results obtained between 5 and 60°C. to 25°C. The results are explained in terms of a loss of water from the hydrated CsDNA complex. It is estimated that about one‐third per cent of the water preferentially hydrated by the DNA is liberated per degree elevation in temperature. Significant errors in buoyant density determinations are made if the thermal expansion coefficient of CsCl solutions is ignored.