Theoretical analysis of the helix-coil transition in positively superhelical DNA at high temperatures

被引:13
作者
Benham, CJ
机构
[1] Department of Biomathematical Sciences, Box
[2] Mount Sinai School of Medicine, New York 1, NY, 10029, Gustave Levy Place
来源
PHYSICAL REVIEW E | 1996年 / 53卷 / 03期
关键词
D O I
10.1103/PhysRevE.53.2984
中图分类号
O35 [流体力学]; O53 [等离子体物理学];
学科分类号
070204 ; 080103 ; 080704 ;
摘要
This paper presents a statistical mechanical analysis of strand separation in a topologically constrained (i.e., superhelical) DNA homopolymer. Our calculations show that positive superhelicity can efficiently stabilize the B-form DNA duplex at temperatures substantially above the transition temperature T-m for denaturation of the linear molecule. Moderate superhelix densities (sigma < 0.08) suffice to keep a DNA molecule virtually entirely in the B-form conformation at temperatures where, if it were relaxed, it would be substantially denatured. This behavior persists up to a predicted critical temperature T-c > T-m. When T > T-c the molecule remains entirely denatured regardless of the amount of superhelicity imposed. The value of T-c is shown to depend on the torsional stiffness C associated with interstrand twisting of the unpaired strands within denatured regions. Thus, experiments that measure T-c would provide another method to evaluate C.
引用
收藏
页码:2984 / 2987
页数:4
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