Abstract
The role of base-pair cooperativity in causing the helix-coil transition or the “melting” of a linear hydrogen-bonded macromolecule like DNA is well known. In the present paper, the melting curve for the covalently closed supercoiled DNA is studied, on the basis of statistical mechanics, by assuming the existence of supercoil-induced cruciforms as significant structural perturbations over the usual regular helical sequence and the bubbles in the premelting region of the macromolecule. In comparison, the nicked circular DNA, like the linear macromolecule, is assumed to consist of the regular helical sequences and the bubbles only. The partition functions are obtained on the basis of the appropriate sequence-generating functions, so that the number of helical units at a given temperature can be determined. The results are compared with the available experimental data in tetraethylammonium bromide (TEA) solution where the effect of the base-pair heterogeneity is minimized. The higher melting point and the flatter melting curve for the supercoiled DNA, as obtained from theory, are found to be in close agreement with the corresponding experimental observation.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
