A proform of secretin with high secretin-like bioactivity

A variant form of the heptacosapeptide amide secretin, with C-terminal -Val-Gly-Lys-Arg instead of valine amide, has been isolated from porcine upper intestinal tissue. Unexpectedly, this triacontapeptide exhibited a substantially higher bioactivity than the heptacosapeptide amide.