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Updated: Apr 12, 2026

Magnetic Tweezers for the Measurement of Twist and Torque
Published on: May 19, 2014
Annealed random copolymer model of the B-Z transition in DNA: torsional responses
Ah-Young Kwon1, Nam-Kyung Lee2, Seok-Cheol Hong3
1Department of Physics, Sejong University, Seoul, South Korea.
Abstract:
Both in vivo and in vitro, specific sequences in double-stranded DNA can adopt the left-handed Z-form when underwound. Recently, the B-Z transition of DNA has been studied in detail in magnetic tweezers experiments by several groups. We present a theoretical description of this transition, based on an annealed random copolymer model. The transition of a switchable sequence is discussed as a function of energetic and geometric parameters of the B- and Z-forms, of the applied boundary conditions, and of the characteristics of the B-Z interface. We address a possible torsional softening upon the B-Z transition. The model can be also applied to other biofilaments with annealed torsional/flexural degrees of freedom.
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