Elastic properties and secondary structure formation of single-stranded DNA at monovalent and divalent salt conditions.

ABSTRACT: 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

SUBMITTER: Bosco A 

PROVIDER: S-EPMC3919573 | biostudies-literature | 2014 Feb

REPOSITORIES: biostudies-literature