Cutting DNA: Mechanics of the topoisomerase
School of Engineering, Aberdeen University, AB24 3, FX Aberdeen, UK
2 Dept. of Applied Mathematics & Theoretical Physics, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 0WA, UK
Corresponding author: email@example.com
Taking the accurate theoretical solutions of Coleman and Swigon for a DNA plasmid in a plectonemic state under imposed link and responsive writhe, we examine in detail the working of the two types of cutting enzyme (topoisomerase Type 1 and topoisomerase Type 2). The mechanical processes involved can generate a plethora of outcomes, all assigning different levels of relaxation to the molecule. Alternative outcomes arise when there are co-existing (meta-) stable equilibrium states. Resolution of the outcome would then require a dynamic analysis of the relaxation process, though the Maxwell criterion can offer some guidance.
© EDP Sciences, Springer-Verlag, 2008