The three analogs of bradykinin are described in which L-proline residue in 3-position of 6-glycine-bradykinin is substituted for sarcosine, glycine, and L-alanine residue respectively. 3-Glycine-bradykinin and its O-acetyl compound are also described. The biological activity of the five analogs is compared with that of bradykinin on an isolated guinea pig ileum.
