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Hairpin-dimer equilibrium of a parallel-stranded DNA hairpin: formation of a four-stranded complex

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Item Type:Article
Title:Hairpin-dimer equilibrium of a parallel-stranded DNA hairpin: formation of a four-stranded complex
Creators Name:Dornberger, U. and Behlke, J. and Birch-Hirschfeld, E. and Fritzsche, H.
Abstract:The 24mer deoxyoligonucleotide 3'-d(T)10-5'-5'-d(C)4- d(A)10-3'(psC4) with an uncommon 5'-p-5'phosphodiester linkage was designed to enable the formation of a hairpin structure with unusual parallel-stranded stem. As reference hairpin structure with an antiparallel-stranded stem, the 24mer 5'-d(T)10-d(C)4-d(A)10-3'(apsC4) was chosen. The behaviour of these oligonucleotides at different temperatures, DNA and salt concentrations was characterised by a combination of UV melting, CD, CD melting, infrared and Raman spectroscopy, infrared melting and analytical ultracentrifugation. The parallel-stranded hairpin structure was found to be formed by psC4 only under conditions of low DNA concentration and low salt concentration. Increase of the NaCl concentration beyond the physiological level or high DNA concentration supports the formation of intermolecular multi-stranded structures. The experimental data are in agreement with a four-stranded complex formed by two molecules of psC4. The base pairing model of this asymmetric four-stranded complex is based on the pyrimidine motif of a triple helix with two bifurcated hydrogen bonds at the O4 of the thymine each directed towards one of the amino protons of both adenines. In contrast, the reference oligonucleotide apsC4 forms only an antiparallel-stranded hairpin under all experimental conditions.
Keywords:Base Composition, Circular Dichroism, Fourier Transform Infrared Spectroscopy, Nucleic Acid Conformation, Oligodeoxyribonucleotides, Raman Spectrum Analysis, Temperature, Ultracentrifugation, Ultraviolet Spectrophotometry
Source:Nucleic Acids Research
Publisher:Oxford University Press
Page Range:822-829
Date:15 February 1997
Official Publication:http://nar.oxfordjournals.org/cgi/content/abstract/25/4/822
PubMed:View item in PubMed

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