Polyelectrolyte properties of single stranded DNA measured using SAXS and single molecule FRET: beyond the wormlike chain model

摘要: Nucleic acids are highly charged polyelectrolytes that interact strongly with salt ions. Rigid, base-paired regions successfully described wormlike chain models, but nonbase-paired single stranded have fundamentally different polymer properties because of their greater flexibility. Recently, attention has turned to nucleic due the growing recognition biological importance, as well availability sophisticated experimental techniques sensitive conformation individual molecules. We investigate polyelectrolyte poly(dT), an important and widely studied model system for flexible acids, in physiologically mixed mono- divalent salt. report measurements form factor interparticle interactions using SAXS, end-to-end distances smFRET, number excess ions ASAXS. present a coarse-grained accounts flexibility, excluded volume, electrostatic these systems. Predictions validated against experiment. also discuss state all-atom, explicit solvent molecular dynamics simulations next step understanding complexities ion polymers.