Theoretical study of DNA's deformation and instability subjected to mechanical stress.

DNA (deoxyribonucleic acid) possesses the ability to alter its conformation in response to stresses. In the case that DNA is mistakenly structured or packed, it can lead to diseases or deformities. Additionally, stretching and compressing of DNA can be useful for some applications. Thus the investigation of the DNA elasticity and stability is necessary. We propose to study the mechanics of a DNA molecule under mechanical stress within the framework of Kirchhoff's rod model. The problem is solved by perturbation method to find equilibrium configurations of DNA at different modes that can be excited. The results show that DNA overwinds under tension of 31 pN, and it begins to unwind beyond 31 pN which is in good agreement with the previous literature. It also suggests that the helical structure is stable under compression less than 367 pN, above that it is unstable. Moreover, the critical values of torsion, modes, the number of turns, and forces leading to the instability are reported. This analytical study could be a groundwork providing better understandings on DNA's deformation and relevant biological processes, and critical parameters affecting to the instability with engineering implications in designing a DNA-based functional nanodevice. [ABSTRACT FROM AUTHOR]