Ionized and wobble base-pairing for bromouracil-guanine in equilibrium under physiological conditions. A nuclear magnetic resonance study on an oligonucleotide containing a bromouracil-guanine base-pair as a function of pH

Lawrence Sowers, M. F. Goodman, R. Eritja, B. Kaplan, G. V. Fazakerley

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71 Citations (Scopus)

Abstract

A one and two-dimensional nuclear magnetic resonance study of a non-selfcomplementary oligonucleotide containing a central 5-bromouracil-guanine pair is reported. For these two bases three types of hydrogen bonding schemes could exist; wobble, rare tautomer and ionized. The two-dimensional spectra of non-exchangeable protons together with onedimensional spectra recorded in water show that at pH 7.0 the predominant species is a right-handed B-form DNA in which the brU · G pair has wobble geometry. On raising the pH we observe a transition monitored by proton chemical shift changes for the brU · G and adjacent base-pairs. The mid-point of the transition was observed at pH 8.6. Spectra recorded at pH 9.8 show that the helix remains intact with B form conformation. It is shown that this high pH form has an ionized brU · G base-pair now in Watson-Crick geometry. Thus under physiological conditions an equilibrium exists between wobble and ionized structures.

Original languageEnglish (US)
Pages (from-to)437-447
Number of pages11
JournalJournal of Molecular Biology
Volume205
Issue number2
DOIs
StatePublished - Jan 20 1989
Externally publishedYes

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Bromouracil
Guanine
Oligonucleotides
Base Pairing
Magnetic Resonance Spectroscopy
Protons
B-Form DNA
Hydrogen Bonding
Water

ASJC Scopus subject areas

  • Virology

Cite this

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title = "Ionized and wobble base-pairing for bromouracil-guanine in equilibrium under physiological conditions. A nuclear magnetic resonance study on an oligonucleotide containing a bromouracil-guanine base-pair as a function of pH",
abstract = "A one and two-dimensional nuclear magnetic resonance study of a non-selfcomplementary oligonucleotide containing a central 5-bromouracil-guanine pair is reported. For these two bases three types of hydrogen bonding schemes could exist; wobble, rare tautomer and ionized. The two-dimensional spectra of non-exchangeable protons together with onedimensional spectra recorded in water show that at pH 7.0 the predominant species is a right-handed B-form DNA in which the brU · G pair has wobble geometry. On raising the pH we observe a transition monitored by proton chemical shift changes for the brU · G and adjacent base-pairs. The mid-point of the transition was observed at pH 8.6. Spectra recorded at pH 9.8 show that the helix remains intact with B form conformation. It is shown that this high pH form has an ionized brU · G base-pair now in Watson-Crick geometry. Thus under physiological conditions an equilibrium exists between wobble and ionized structures.",
author = "Lawrence Sowers and Goodman, {M. F.} and R. Eritja and B. Kaplan and Fazakerley, {G. V.}",
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AU - Sowers, Lawrence

AU - Goodman, M. F.

AU - Eritja, R.

AU - Kaplan, B.

AU - Fazakerley, G. V.

PY - 1989/1/20

Y1 - 1989/1/20

N2 - A one and two-dimensional nuclear magnetic resonance study of a non-selfcomplementary oligonucleotide containing a central 5-bromouracil-guanine pair is reported. For these two bases three types of hydrogen bonding schemes could exist; wobble, rare tautomer and ionized. The two-dimensional spectra of non-exchangeable protons together with onedimensional spectra recorded in water show that at pH 7.0 the predominant species is a right-handed B-form DNA in which the brU · G pair has wobble geometry. On raising the pH we observe a transition monitored by proton chemical shift changes for the brU · G and adjacent base-pairs. The mid-point of the transition was observed at pH 8.6. Spectra recorded at pH 9.8 show that the helix remains intact with B form conformation. It is shown that this high pH form has an ionized brU · G base-pair now in Watson-Crick geometry. Thus under physiological conditions an equilibrium exists between wobble and ionized structures.

AB - A one and two-dimensional nuclear magnetic resonance study of a non-selfcomplementary oligonucleotide containing a central 5-bromouracil-guanine pair is reported. For these two bases three types of hydrogen bonding schemes could exist; wobble, rare tautomer and ionized. The two-dimensional spectra of non-exchangeable protons together with onedimensional spectra recorded in water show that at pH 7.0 the predominant species is a right-handed B-form DNA in which the brU · G pair has wobble geometry. On raising the pH we observe a transition monitored by proton chemical shift changes for the brU · G and adjacent base-pairs. The mid-point of the transition was observed at pH 8.6. Spectra recorded at pH 9.8 show that the helix remains intact with B form conformation. It is shown that this high pH form has an ionized brU · G base-pair now in Watson-Crick geometry. Thus under physiological conditions an equilibrium exists between wobble and ionized structures.

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