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Position-dependent effects on stability in tricyclo-DNA modified oligonucleotide duplexes

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Publication date 2011
Author Ittig D., Gerber A. B., Leumann C. J.,
Project Chemically modified Oligonucleotides for Biotechnology and Material Sciences
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Original article (peer-reviewed)

Journal Nucleic Acids Research
Volume (Issue) 39
Page(s) 373 - 80
Title of proceedings Nucleic Acids Research

Abstract

A series of oligodeoxyribonucleotides and oligoribonucleotides containing single and multiple tricyclo(tc)-nucleosides in various arrangements were prepared and the thermal and thermodynamic transition profiles of duplexes with complementary DNA and RNA evaluated. Tc-residues aligned in a non-continuous fashion in an RNA strand significantly decrease affinity to complementary RNA and DNA, mostly as a consequence of a loss of pairing enthalpy DeltaH. Arranging the tc-residues in a continuous fashion rescues T(m) and leads to higher DNA and RNA affinity. Substitution of oligodeoxyribonucleotides in the same way causes much less differences in T(m) when paired to complementary DNA and leads to substantial increases in T(m) when paired to complementary RNA. CD-spectroscopic investigations in combination with molecular dynamics simulations of duplexes with single modifications show that tc-residues in the RNA backbone distinctly influence the conformation of the neighboring nucleotides forcing them into higher energy conformations, while tc-residues in the DNA backbone seem to have negligible influence on the nearest neighbor conformations. These results rationalize the observed affinity differences and are of relevance for the design of tc-DNA containing oligonucleotides for applications in antisense or RNAi therapy.
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