title: Thermodynamic study of internal loops in oligoribonucleotides: symmetric loops are more stable than asymmetric loops.
abstract: Thermodynamic parameters for internal loops of unpaired adenosines in oligoribonucleotides have been measured by optical melting studies. Comparisons are made between helices containing symmetric and asymmetric loops. Asymmetric loops destabilize a helix more than symmetric loops. The differences in free energy between symmetric and asymmetric loops are roughly half the magnitude suggested from a study of parameters required to give accurate predictions of RNA secondary structure [Papanicolaou, C., Gouy, M., & Ninio, J. (1984) Nucleic Acids Res. 12, 31-44]. Circular dichroism spectra indicate no major structural difference between helices containing symmetric and asymmetric loops. The measured sequence dependence of internal loop stability is not consistent with approximations used in current algorithms for predicting RNA secondary structure.
authors.affiliation: Department of Chemistry, University of Rochester, New York 14627.
authors.forename: A E
authors.initials: AE
authors.lastname: Peritz
authors.forename: R
authors.initials: R
authors.lastname: Kierzek
authors.forename: N
authors.initials: N
authors.lastname: Sugimoto
authors.forename: D H
authors.initials: DH
authors.lastname: Turner
mesh_terms: D001483:Base Sequence; D002942:Circular Dichroism; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009843:Oligoribonucleotides / Q000138:chemical synthesis / Q000737:chemistry*; D012313:RNA / Q000138:chemical synthesis / Q000737:chemistry*; D013329:Structure-Activity Relationship; D013816:Thermodynamics
chemical_list: D009843:Oligoribonucleotides; D012313:RNA