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Molecular orbital calculations of the long‐range proton‐proton coupling constants in purine and pyrimidine nucleosides
Author(s) -
GiessnerPrettre C.,
Pullman B.
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560070736
Subject(s) - furanose , pyrimidine , chemistry , dihedral angle , glycosidic bond , purine , proton , coupling constant , ring (chemistry) , molecular orbital , computational chemistry , crystallography , stereochemistry , molecule , hydrogen bond , physics , organic chemistry , enzyme , particle physics , quantum mechanics
The molecular orbital INDO method is used for the calculation of long‐range NMR proton‐proton coupling constants between H 1 , and protons of the base and between the protons of the furanose ring in purine and pyrimidine nucleosides. The computations show that the couplings between H 1 , and the protons of the base are negligible in the purine nucleosides and are very sensitive to the torsion angle about the glycosidic bond in pyrimidine nucleosides. For uridine and its derivatives the calculated J 1, 5 are in agreement with experiment for an anti conformation of these compounds. For α‐ and β‐pseudouridines, J 1, 6 is important and may be large for anti as well as syn conformations. The long‐range couplings between the protons of the furanose ring vary little with the puckering of the sugar.