Structure of Vasopressin and Oxytocin	

The genes encoding vasopressin and oxytocin are tightly linked on chromosome 20. The structure of the neurohypophysial hormones vasopressin and oxytocin (Fig. 5.5) was elucidated, and their synthesis completed, by 1954. 
Arginine vasopressin (AVP) is the antidiuretic hormone of most mammals, although the pig family uses lysine vasopressin. 
The vasopressins are basic molecules with isoelectric points in the region of pH 9–10, while oxytocin is more neutral. The ring is essential for biological activity. Position 8 plays a key role in determining oxytocic or vasopressor characteristics. The more basic the amino acid in this position, the more vasopressor activity the molecule possesses. 

See also:
• Vasopressin
• Analogues of Vasopressin
• Oxytocin