The Synthesis and Pharmacological Properties of Deamino-4-decarboxamido-oxytocin (1-ß-Mercaptopropionic Acid-4-
-Aminobutyric Acid-Oxytocin)
Luis A. Branda 1, Stefania Drabarek 1, and Vincent du Vigneaud 1
From the
1 From the Department of Biochemistry, Cornell University Medical College, New York, New York 10021
Deamino-4-decarboxamido-oxytocin, an analogue of oxytocin in which the free amino group of the half-cystine residue at position 1 and the carboxamide group of the glutamine residue at position 4 have been replaced by hydrogen, has been synthesized. The protected polypeptide intermediate for this compound, prepared by the stepwise p-nitrophenyl ester method, was converted by the action of sodium in liquid ammonia into the disulfhydryl intermediate from which the analogue was obtained by oxidation with potassium ferricyanide. It was subsequently isolated either by countercurrent distribution or by partition chromatography on Sephadex, and was obtained in crystalline form from an aqueous solution.
Deamino-4-decarboxamido-oxytocin possesses approximately 
of the avian vasodepressor activity, 
of the oxytocic activity, and 
of the milk-ejecting activity of oxytocin. These potencies are considerably higher than the corresponding potencies of 4-decarboxamido-oxytocin. The deamino analogue has extremely low antidiuretic activity and no detectable pressor activity.
Submitted on January 26, 1966
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