A statistical mechanical model for predicting B-DNA curvature and flexibility

A statistical mechanical model taking into account the symmetric twisting, tilting, sliding fluctuations and asymmetric rolling fluctuations has been proposed to predict the macroscopic curvature and flexibility of B-DNA. Bas ed on the statistical data of structural parameters of double helix in nucl eic acid database and the related theoretical analysis, the equilibrium ang ular parameters (Omega, rho and tau) describing the orientation of successi ve base-pair planes, the translation parameters (D-y) along the long axis o f neighboring base-pair step and the corresponding force constants are arra nged for ten dimers appropriately. Under the assumption of independent angu lar parameters, independent base-pair steps and a simple energy function, w e can calculate the macroscopic curvature and the flexibility of DNA sequen ces through the transformation matrix <R > and the Boltzmann ensemble avera ge. The predictions on curvature and flexibility of DNA have been compared with the corresponding experimental data. The agreement is remarkably good. It is demonstrated that the lowering of the temperature does increase the DNA curvature. (C) 2000 Academic Press.