Unzipping of a double-stranded block copolymer DNA by a periodic force

Using Monte Carlo simulations, we study the hysteresis in unzipping of a double-stranded block copolymer DNA with -A(n)B(n)- repeat units. Here A and B represent two different types of base pairs having two and three bonds, respectively, and 2n represents the number of such base pairs in a unit. The end of the DNA are subjected to a time-dependent periodic force with frequency (omega) and amplitude (g(0)) keeping the other end fixed. We find that the equilibrium force-temperature phase diagram for the static force is independent of the DNA sequence. For a periodic force case, the results are found to be dependent on the block copolymer DNA sequence and on the base pair type on which the periodic force is acting. We observe hysteresis loops of various shapes and sizes and obtain the scaling of loop area both at low- and high-frequency regimes.

Automated summary

Using Monte Carlo simulations, hysteresis behavior in unzipping of a double-stranded block copolymer DNA with repetitive units is studied. The equilibrium force-temperature phase diagram for static force is found to be independent of DNA sequence, while results for periodic force case depend on the DNA sequence and the type of base pairs. Various shapes and sizes of hysteresis loops are observed, and the scaling of loop area is obtained in low- and high-frequency regimes.