Conformational Transitions in Drug-DNA Complexes

Molecular interaction of the drug with DNA is a field of high topical interest and may have a great importance to its biological activity. A number of techniques committed to drug-DNA interactions are evolved. The present investigation described theoretical analysis of steroid diamine (dipyrandium) and tricyclic hetero-aromatic molecule (thionine) binding with DNA duplex by using an amended Zimm and Bragg theory. These studies explain the melting behavior and heat capacity of DNA with and without drugs binding. The results of both the studies suggested that the DNA molecule is an extremely cooperative structure and when drugs bind to it the cooperativity is not so much disturbed. Thus, the amended Zimm and Bragg theory can be effectively applied to it. It generates the experimental transition profile and ¿-point heat capacity anomaly successfully. The results obtained will allow us to evaluate the thermodynamic profile of the binding process. This theoretical analysis of small molecules binding with nucleotide may be extended to other synthetic and natural DNA and can also be useful in order to understand bimolecular interaction and in the process of drug development.