An experimental study of the temperature-dependent DNA elasticity using optical tweezers

Abstract

Temperature plays a key role in all biological processes. Slight changes of temperature may lead to completely di erent behaviors of biological systems. In fact, living matter carry out its function in a small range of temperature. Therefore, it is interesting to study and understand what is the effect of temperature in biological systems. Single-stranded DNA (ssDNA) is one of the most relevant molecules in biological processes, providing us an excellent scenario to understand how the temperature a ect its properties. In this project we aim to understand and characterize the elastic response of ssDNA at di erent temperatures. We have used the Laser Optical Tweezers (LOT) technique in order to measure the Force-Distance Curves (FDC) of ssDNA under the e ect of a mechanical force at di erent temperatures. By tting the stretching response of ssDNA to two semi exible polymer models we have obtained the temperature dependence of the elastic parameters. We have found that persistence length and Kuhn length increase with temperature while the stretching modulus seems to be insensitive to temperature changes. Finally, we have found that the persistence length is proportional to the Debye screening length and that it varies with temperature according to a power law with exponent < 1.