circular dichroism spectroscopy , absorption spectroscopy , measurements of tm values , sedimentation analysis and electron microscopy were used to study properties of calf thymus dna in methanol-water mixtures as a function of monovalent cation ( na+ or cs+ ) concentration and also in the presence of divalent cations ca2+ , mg2+ , and mn2+ .
C0007447
cation
C0007448
divalent cations