Persistence length changes dramatically as RNA folds.
We determine the persistence length l(p) for a bacterial group I ribozyme as a function of concentration of monovalent and divalent cations by fitting the distance distribution functions P(r) obtained from small angle x-ray scattering intensity data to the asymptotic form of the calculated P(WLC)(r) for a wormlike chain. The l(p) values change dramatically over a narrow range of Mg(2+) concentration from approximately 21 Angstroms in the unfolded state (U) to approximately 10 Angstroms in the compact (I(C)) and native states. Variations in l(p) with increasing Na(+) concentration are more gradual. In accord with the predictions of polyelectrolyte theory we find l(p) alpha 1/kappa(2) where kappa is the inverse Debye-screening length.
TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland 21218, USA.
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Caliskan
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Hyeon
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Perez-Salas
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Briber
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Woodson
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Thirumalai
D003198:Computer Simulation; D008956:Models, Chemical; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D012329:RNA, Bacterial / Q000737:chemistry*; D016337:RNA, Catalytic / Q000737:chemistry*
D012329:RNA, Bacterial; D016337:RNA, Catalytic