Thermodynamic Anomaly and Transitions in Various States of Poly (dG-dC)

Abstract

Zimm and Bragg theory of (Remark: Graphics omitted.) transition has been modified to explain (Remark: Graphics omitted.) transition in polynucleotides, in particular (Remark: Graphics omitted.) transitions in poly (dG-dC) and poly (dG-me⁵ dC). Lambda anomaly in specific heat measurements around the transition point have also been explained by a further modification of the same theory. Theoretical results are found to be in good agreement with the experimental data. The Nucleation parameter which determines the sharpness of transition and depends on the extent and strength of cooperativity, is consistent with the stabilization/destabilization of the ordered states under various environmental conditions, e.g. methylation of cytosine residue at C5 position or change in the cationic concentration of the solvent.