Chemical and biological properties of porcine secretin and secretin analogues modified in positions 3 and 4.

The synthesis of secretin does not offer fundamental difficulties any longer. The problem of the stability of the hormone seems to be solved from a practical point of view. However, the mechanism of the inactivation of secretin in solution is not yet satisfactorily explained, alpha-beta Rearrangement of the Asp-Gly bond may play a role, but some observations indicate that inactivation is not a straight reaction. Like secretion [Ala-4] secretin shows beta-sympathomimetic activity. The availability of a suitable depot preparation permits physiological studies with secretin and its analogues after subcutaneous administration.