期刊
NUCLEIC ACIDS RESEARCH
卷 42, 期 3, 页码 2064-2074出版社
OXFORD UNIV PRESS
DOI: 10.1093/nar/gkt1089
关键词
-
资金
- Erasmus Placement grant [KTEU EP 4]
- Associazione Italiana Ricerca Cancro [12214]
- Institucio Catalana de Recerca i Estudis Avancats
- Human Frontier Science Program [RGP55-2008]
- Spanish Ministry of Economy and Competitiveness [FIS2010-19342]
- European Union Seventh Framework Programme [308850]
Single-stranded DNA (ssDNA) plays a major role in several biological processes. It is therefore of fundamental interest to understand how the elastic response and the formation of secondary structures are modulated by the interplay between base pairing and electrostatic interactions. Here we measure force-extension curves (FECs) of ssDNA molecules in optical tweezers set up over two orders of magnitude of monovalent and divalent salt conditions, and obtain its elastic parameters by fitting the FECs to semiflexible models of polymers. For both monovalent and divalent salts, we find that the electrostatic contribution to the persistence length is proportional to the Debye screening length, varying as the inverse of the square root of cation concentration. The intrinsic persistence length is equal to 0.7nm for both types of salts, and the effectivity of divalent cations in screening electrostatic interactions appears to be 100-fold as compared with monovalent salt, in line with what has been recently reported for single-stranded RNA. Finally, we propose an analysis of the FECs using a model that accounts for the effective thickness of the filament at low salt condition and a simple phenomenological description that quantifies the formation of non-specific secondary structure at low forces.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据