Still Elusive – Pd(II)-Mediated Base Pairing by an Acetophenone Oxime Palladacycle within 15N-Labelled Double-Helical Oligonucleotides |
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Authors: | Maaret Toiviala Vesa Kleemola Sajal Maity Tuomas Lönnberg |
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Institution: | Department of Chemistry, University of Turku, Henrikinkatu 2, 20500 Turku, Finland |
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Abstract: | Both α and β anomers of an acetophenone C-nucleoside were synthesized and incorporated in the middle of short oligodeoxynucleotides. The ketone oligonucleotides were converted to 15N-labelled oxime oligonucleotides by treatment with 15N-hydroxylamine and, finally, cyclopalladated by treatment with lithium tetrachloropalladate. Comparison of the UV melting profiles of duplexes bearing the β anomer of either the palladacyclic or the metal-free oxime C-nucleoside suggested formation of a stable Pd(II)-mediated base pair, especially with adenine or thymine as the base pairing partner. Melting profiles of the corresponding duplexes bearing the α anomer were much more convoluted, precluding meaningful comparison. 15N NMR spectra were obtained for the β anomeric oxime oligonucleotide as well as its palladacyclic derivative but the signals unfortunately diminished below detection limit when the latter was hybridized with a complementary strand placing a 15N3-labelled thymine opposite to the palladacyclic residue. |
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Keywords: | base pairing isotopic labeling NMR spectroscopy oligonucleotides palladium |
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