Open AccessProton‐Magnetic‐Resonance Study of the Solution Conformation of the α and β Anomers of 5‐Ethyl‐2′‐deoxyuridine
Author(s) -
REMIN Mieczyslaw,
EKIEL Irena,
SHUGAR David
Publication year - 1975
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1975.tb04058.x
Subject(s) - deoxyribose , anomer , chemistry , stereochemistry , conformational isomerism , alkane stereochemistry , chemical shift , glycosidic bond , substituent , side chain , nuclear magnetic resonance spectroscopy , ring (chemistry) , crystallography , nucleic acid , organic chemistry , crystal structure , molecule , enzyme , biochemistry , polymer
1 The α and β anomers of 5‐ethyl‐2′‐deoxyuridine, the latter of which is a thymidine analogue with antiviral activity, have been subjected to a conformational analysis in aqueous medium by proton magnetic resonance (PMR) spectroscopy with the aid of the iteration program LAOCCOON‐3. 2 The results demonstrated a marked preference for the conformation C‐2′‐ endo of the deoxyribose rings of both anomers; and this appears to be an inherent property of the deoxyribose ring itself. As regards the exocyclic 5′‐CH 2 OH group, the β anomer exhibited a preference for the gauchegauche conformation; in the case of the α anomer, all three classical conformers were equally favoured. 3 A particularly extensive analysis of the conformation about the glycosidic bond, based on the chemical shifts of several sugar protons, pointed to the conformation anti for both anomers. 4 The data for the protons of the 5‐ethyl side chain are in accord with a symmetrical distribution of the rotamers of this substituent relative to the plane of the pyrimidine ring. 5 The overall findings are compared with those earlier reported for the α and β anomers of thymidine, as well as a number of other nucleosides, nucleotides and polynucleotides. 6 PMR spectral data were similarly utilised to perform a conformational analysis of the α and β anomers of 5‐ethyl‐2′‐deoxycytidine, an analogue of 5‐methyldeoxycytidine; the results did not differ appreciably from those for the 5‐ethyldeoxyuridine anomers.