Development of a Model for DNA Supercoiling
The supercoiling of closed circular DNA in vivo is regulated by a class of enzymes called topoisomerases, and it is known to play an important role in gene expression. Negative supercoiling can be induced in vitro by DNA gyrase, or by unwinding the double helix with intercalating drugs, followed by relaxation with topoisomerase and then removal of the intercalator. Supercoiling pressure is often used to promote the formation of unusual DNA structures, for example, Z-DNA and cruciforms. The study of DNA supercoiling is thus an important problem biologically and because of its use as an agent for inducing other structures. The topological issues surrounding DNA supercoiling have been extensively studied (Benham, 1985; 1986; White and Bauer, 1986), and they have been applied to the explanation of a number of events in recombination (Wasserman et al, 1985; Cozzarelli et al, 1985; Geliert and Nash, 1987).
KeywordsDouble Helix Roll Angle Twist Angle Potential Energy Function Harmonic Potential
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