Elastic properties of a single-stranded charged homopolymeric ribonucleotide

The elastic properties of poly(U), homopolymeric single-stranded RNA molecules that lack any base pairing and stacking interactions and conform to a random-coil structure were investigated. It was found that in its natural state under room temperature, both the base pairing and stacking interactions are negligible. Using a single-molecule stretching experiments, it was shown that the elastic properties could be described by a wormlike chain model for polymer elasticity rather than by a freely joined chain model used commonly for single-stranded DNA. It was also shown that at low [NA⁺], introduction of a scale-dependent persistence length is required to account for elastrostatic contributions.