Identification of mesotocin, lysine vasopressin, and phenypressin in the eastern gray kangaroo (Macropus giganteus).

The neurohypophysial hormones of the eastern gray kangaroo (Macropus giganteus) have been isolated through molecular sieving and paper chromatoelectrophoresis. One oxytocin-like and two vasopressin-like peptides have been found. These peptides have been characterized by amino acid analysis. Mesotocin ([Ile8]-oxytocin), has been identified both by amino acid composition and by behavior in partition chromatography. Lysine vasopressin has been characterized by amino acid composition and by partial amino acid sequence determination. Phenypressin ([Phe2]-arginine vasopressin) has been identified by amino acid composition. Lysine vasopressin is about twice as abundant as phenypressin. These three peptides have previously been identified in two other macropodids, namely, the red kangaroo and the tammar wallaby, and seem to be present in all the family Macropodidae. The evolution of neurohypophysial hormones is discussed in regard to these results.