Nucleic Acids Research, Vol 25, Issue 23 4758-4763, Copyright © 1997 by Oxford University Press
X Huang, P Yu, E LeProust and X Gao
We describe herein the use of a 2H-labeling strategy to achieve specific
assignments of considerably overlapped cross peaks in the 1H- NMR spectrum
of a DNA trinucleotide repeat sequence. Our strategy focuses on
site-specific 2H-labeling of base moieties to simplify the NMR spectral
regions which contain the major portion of the structural information. To
achieve efficient preparation of 2H8- or 2H6-labeled DNA and RNA
nucleosides and nucleotides, the existing synthetic and purification
procedures were significantly improved. Our experiments demonstrate that
pyrimidine H6 deuteration reactions may be carried out using non-deuterated
base reagents with DMSO-d6 as a 2H donor. These reactions are simple and
economic to perform and produce base deuterated nucleosides and nucleotides
in high yield. The 2H-labeled residues have been incorporated into
oligonucleotides with minor modifications of the existing reaction
conditions. Using the homologous CGG repeat sequence, d(CGG)5, as an
example, the effectiveness of the site-specific base deuteration strategy
is demonstrated. In the otherwise extensively overlapped spectra of
d(CGG)5, 2H-labeling has permitted unambiguous identification of a
sequential connectivity at a central CG step and confirmation of several
other NOE assignments. This information is critical for elucidation of the
structure and the folding of the CGG repeat sequences and will contribute
to the intensive effort to understand the mechanisms of triplet expansion,
which has been implicated in the development of a number of hereditary
neurodegenerative diseases. In addition to the two dimensional spectral
simplification in a key spectral region using site-specific 2H8/2H6-
labeling, the potential applications of the prescribed strategy in
homonuclear three dimensional experiments are also discussed.
ARTICLES
An efficient and economic site-specific deuteration strategy for NMR studies of homologous oligonucleotide repeat sequences
Department of Chemistry, University of Houston, Houston, TX 77204-5641, USA.
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