持续时间
DNA
分子
光学镊子
离子强度
生物物理学
埃
双绞线
结晶学
化学
碱基对
磁镊
化学物理
水溶液
物理
生物
光学
生物化学
物理化学
有机化学
作者
Steven B. Smith,Yujia Cui,Carlos Bustamante
出处
期刊:Science
[American Association for the Advancement of Science (AAAS)]
日期:1996-02-09
卷期号:271 (5250): 795-799
被引量:2508
标识
DOI:10.1126/science.271.5250.795
摘要
Single molecules of double-stranded DNA (dsDNA) were stretched with force-measuring laser tweezers. Under a longitudinal stress of ∼65 piconewtons (pN), dsDNA molecules in aqueous buffer undergo a highly cooperative transition into a stable form with 5.8 angstroms rise per base pair, that is, 70% longer than B-form dsDNA. When the stress was relaxed below 65 pN, the molecules rapidly and reversibly contracted to their normal contour lengths. This transition was affected by changes in the ionic strength of the medium and the water activity or by cross-linking of the two strands of dsDNA. Individual molecules of single-stranded DNA were also stretched giving a persistence length of 7.5 angstroms and a stretch modulus of 800 pN. The overstretched form may play a significant role in the energetics of DNA recombination.
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