MODEL OF THE SPLITTING OF DNA-MOLECULES

A model is proposed for the splitting (i.e., doubling) of DNA molecule s. This process is interpreted as clothing of a curve (describing the equilibrium conformation of the molecule) with a vector field q which models the hydrogen bonds between the two polynucleotide chains that f orm the double helix of DNA. Fluctuations of this field result in the renormalization of the torque that gives rise to the supercoiling of D NA (which actually occurs during replication). It is also shown that t he local breaking of hydrogen bonds, which occurs under the action of temperature (or biochemical factors), results in delocalized deformati on of the curve and a torque distributed on scales on the order of the persistent length. The expression derived for this torque makes it po ssible to relate the energy characteristics, measured in independent e xperiments, of the hydrogen bonds with the geometric parameters of the supercoil. (C) 1995 American Institute of Physics.