Relaxation in biological macromolecules and application of theory to the investigation of secondary structure of DNA

Abstract

Using a statistical mechanical approach we have shown that, in the case of large perturbations, the fraction of helicity at time t can be factored into two terms—a chain length dependent term which is a function of the dispersity of macromolecules and a sigmoidal term which depends on the nucleation parameter, σ, but not on chain lengths. The analytic expression for the fraction of helicity obtained from our approach is very similar to that obtained by Trifonov et al. for an irreversible conformational transformation. Our approach, however, uses one less parameter than that of Trifonov et al. and, moreover, is applicable to the reversible as well as irreversible cases. We have applied our theory to the denaturation of DNA under the action of formaldehyde and found excellent agreement between the theory and experiment.