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Hydrogen bonding in complexes of adenosine and 4‐thiouridine: a low‐temperature NMR study
Author(s) -
Basilio Janke Eline M.,
Dunger Anita,
Limbach HansHeinrich,
Weisz Klaus
Publication year - 2001
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.945
Subject(s) - chemistry , hydrogen bond , acceptor , proton nmr , solvent , molecular structure of nucleic acids: a structure for deoxyribose nucleic acid , molecule , crystallography , stereochemistry , base pair , dna , organic chemistry , biochemistry , physics , condensed matter physics
Abstract NMR experiments were performed on the association of the two sugar‐protected nucleosides 2′‐deoxy‐4‐thiouridine and 2′‐deoxyadenosine in solution. Using an aprotic CDClF 2 –CDF 3 solvent mixture, low‐temperature measurements allowed the observation of individual hydrogen‐bonded complexes in the slow exchange regime. 2D NOE experiments acquired at 128 K show the preferential formation of a ternary complex with two thiouridine nucleosides simultaneously bound at the Watson–Crick and Hoogsteen site of adenosine at all molar ratios. There is no indication of the 4‐thiocarbonyl group involved as proton acceptor in a hydrogen bond to the adenine base to a significant extent. A more downfield chemical shift together with a smaller 1 J ( N , H ) scalar coupling of the Watson–Crick‐bound imino proton in specifically 3‐ 15 N‐labeled thiouridine points to a stronger Watson–Crick than the Hoogsteen hydrogen bond. Copyright © 2001 John Wiley & Sons, Ltd.