Molecular conformation of prostaglandin A 1

Abstract

The crystal and molecular structure of prostaglandin A 1 (PGA 1) has been determined by X-ray diffraction. (Space group P2 12 12 1, a = 18.10 A ̊ A , b = 21.09 A ̊ A , c = 5.42, Z = 4) . Comparison of the structure of PGA 1 with that of PGF 1β (determined previously as the tribromobenzoate) indicates significant differences in the relative intramolecular side chain orientations. However, conformation and torsional angles within each side chain of PGA 1 are retained with little or no change in comparison with PGF 1β, indicating the presence of the C 15-bromobenzoate groups in the latter have had little effect in altering internal side chain conformation in the solid state. The overall differences in relative side chain orientation in PGA 1 are attributable to chemical and conformational changes in the substituted cyclopentane moiety (C 8-C 12).