ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 29, Number 3
JKCSEZ 29(3)
June 20, 1985 

An anomalous absorbance-temperature profile of calf thymus DNA, having a trough preceding the initiation of the melting, occurs at the spermine concentration, where the DNA collapses into a compact structure. The cooperativity, enthalpy, and the midpoint of the phase transition to the trough region are more sensitive to ethidium bromide than those of the Tm region. As the concentration of ethidium bromide added is increased, the peak size of the trough is decreased, while the Tm remains essentially constant.