Utilizad este identificador para citar o enlazar este documento: http://hdl.handle.net/2072/227927

Elastic properties and secondary structure formation of single-stranded DNA at monovalent and divalent salt conditions
Bosco, Alessandro; Camuñas Soler, Joan; Ritort Farran, Fèlix
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 0.7 nm 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.
09-04-2014
Reparació de l'ADN
Biofísica
Àcids nucleics
Aparells i instruments científics
Sal
Elasticitat
DNA repair
Biophysics
Nucleic acids
Scientific apparatus and instruments
Salt
Elasticity
cc-by-nc (c) Bosco, Alessandro et al., 2013
http://creativecommons.org/licenses/by-nc/3.0/es
Artículo
info:eu-repo/semantics/publishedVersion
Oxford University Press
         

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