EFFECTS OF COMPENSATORY SOLUTES ON DNA AND CHROMATIN STRUCTURAL ORGANIZATION IN SOLUTION

We investigated the effect of glycine and other osmotic effectors on D NA and chromatin precipitation by mono-, di- and multivalent cations a nd histone H1. The addition of these compounds drastically reduces the precipitation effects with an efficiency in the order taurine > glyci ne > proline and sorbitol > inositol > betaine. Aminocarboxylic acids with increasing distance between the charged C- and N-terminal groups displayed enhanced efficiency in the protection effect against DNA pre cipitation. We interpreted these observations on the basis of Manning' s counterion condensation theory, taking into account the increase in dielectric constant upon osmotic effector addition. Na-23-NMR was used to evidence sodium counterions release as a result of this increase i n dielectric constant. (C) 1997 Elsevier Science Inc.