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Proton magnetic resonance study of nucleosides, nucleotides, and dideoxynucleoside monophosphates containing a syn pyrimidine base
Author(s) -
Niemczura Walter P.,
Hruska Frank E.,
Sadana Krishna L.,
Loewen Peter C.
Publication year - 1981
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1981.360200809
Subject(s) - chemistry , conformational isomerism , dimer , thymine , uracil , nucleotide , stereochemistry , cyclobutane , ring (chemistry) , pyrimidine , crystallography , base (topology) , alkane stereochemistry , resonance (particle physics) , pyrimidine dimer , monomer , molecule , dna , biochemistry , crystal structure , dna damage , polymer , mathematical analysis , mathematics , organic chemistry , gene , physics , particle physics
Proton magnetic resonance data have been obtained for 6‐methyl‐2′‐deoxyuridine (dT*), its 3′‐ and 5′‐monophosphates, and its 3′,5′‐diphosphate, as well as for the corresponding thymine derivatives. The synthesis of the dideoxynucleoside monophosphates—d(TpT), d(T*pT), d(TpT*), and d(T*pT*)—was accomplished, and spectral data were obtained for these four dimers. The data show that the 6‐methyluracil base prefers the syn conformation about the N ‐glycosyl bond at the monomer and dimer levels. The presence of the syn base leads to increases in the cis couplings of the sugar ring, J 1′2″ and J 2′3′ , which indicate a trend towards eclipsing of the substituents on the C1′‐C2′ and C2′‐C3′ fragments. This trend is discussed in terms of changes in the pseudorotational parameters which describe the pucker of the ring. The syn base destabilizes the g + conformer about the C4′‐C5′ bond, leading to a preference for the t conformer in all dT* residues at the monomer and dimer levels. Preliminary work on the formation of cyclobutane‐type photodimers in d(T*pT) and d(T*pT*) is discussed and presented as evidence for the capability of the syn 6‐methyluracil base to form base‐stacked complexes.