Denaturation of DNA at high salt concentrations

Abstract

Cations present in the solution are important for the stability of two negative strands of DNA molecules. Experimental as well as theoretical results show that the DNA molecule is more stable as the concentration of salt (or cations) increases. It is known that the two strands of DNA molecule carry negative charge due to phosphate group along the strands. These cations act as a shielding particles to the two like charge strands. Recently, in an experiment it is shown that there is a critical value in the concentration of salts (or cations) that can stabilize the helical structure of DNA. If one add more salt in the solution beyond this critical value, the stability of the DNA molecule will disrupt. In this work we study the stability of DNA molecules at higher concentrations. How the stability at higher concentration can be explained through some theoretical calculations is the aim of this manuscript. We consider the PBD model with proper modifications that can explain the negative stability of the molecule at higher concentration. Our findings are in close match with the experimental results.