In:
Canadian Journal of Chemistry, Canadian Science Publishing, Vol. 65, No. 2 ( 1987-02-01), p. 271-276
Abstract:
Crystals of 2′,5′-anhydroarabinosylcytosine hemihydrate belong to the monoclinic space group P2 1 . The cell dimensions are a = 9.643(2), b = 10.328(1), c = 10.544(2) Å, β = 94.55(1)°. X-ray intensity data were measured on a diffractometer and the structure was determined by direct methods. Least-squares refinement, which included all nucleoside hydrogen atoms, converged at R = 0.041 for 2298 observed reflections. The asymmetric unit contains two molecules of the nucleoside and one molecule of water. In both nucleoside molecules, the conformation about the glycosyl bond is and, with X CN values of 15.5(3) and 26.3(3)°, respectively. In the bicyclic sugar moiety, the arabinofuranose rings adopt a C(3′)exo/C(2′)endo conformation and are highly puckered (τ m = 57°). The solution conformation was studied by 1 H and 13 C nmr spectroscopy. A difference nOe proton nmr spectrum and 3 J(C,H) coupling constants reveal an anti conformation in solution, with torsion angles very similar to those obtained from X-ray analysis. A comparison of observed 3 J(H,H) coupling constants with those calculated on the basis of a modified Karplus equation shows significant differences, probably due to the presence of the bicyclic system.
Type of Medium:
Online Resource
ISSN:
0008-4042
,
1480-3291
Language:
English
Publisher:
Canadian Science Publishing
Publication Date:
1987
detail.hit.zdb_id:
1482256-8
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