Cleavage of cholecystokinin with enterokinase

Abstract
The C-terminal octapeptide amide, 8-CCK [cholecystokinin] was rapidly cleaved by (bovine) enterokinase from 2 larger molecular forms of (porcine) cholecystokinin (33-CCK and 39-CCK). This could be expected from the earlier described specificity of enterokinase. An unexpected additional cleavage of an arginyl-isoleucyl bond in the sequence ...His-Arg-Ile... also occurred.