Conformations of Prostaglandin F$_{2\alpha}$ and Recognition of Prostaglandins by Their Receptors

• Published in: Science (American Association for the Advancement of Science) 1977-09, Vol.197 (4307), p.1003-1005
• Main Authors: Langs, David A., Erman, Mary, DeTitta, George T.
• Format: Article
• Language: English
• Subjects: Atoms; Chemical bonding; Epithelium; Geometry; Molecules; Oxygen; Pigments; Prostaglandins; Receptors; Torsion
• ISSN: 0036-8075; 1095-9203

The conformation of prostaglandin F$_{2\alpha}$ (PGF$_{2\alpha}$) has been determined by x-ray diffraction techniques. Two independent conformers of PGF$_{2\alpha}$, studied as the tris(hydroxymethyl)methylamine salt, are observed to adopt the familiar "hairpin" conformation with the α and ω chains aligned roughly parallel. The conformers differ in ring conformation and at the C(17)-C(18) bond, one adopting a C(9) envelope ring conformation and a trans geometry at the C(17)-C(18) bond, while the other adopts a C(8) envelope ring conformation and a novel gauche geometry about C(17)-C(18). Comparison of the conformation of PGF$_{2\alpha}$ with that of prostaglandin E$_{2}$ suggests a recognition mechanism which would permit PGF$_{2\alpha}$ and prostaglandin E receptors to distinguish between the two potent prostaglandins. The recognition model explains much of the binding data for the PGF$_{2\alpha}$ receptor in the corpus luteum and predicts the existence of an interesting PGF$_{2\alpha}$ analog.