ISOLATION AND CHARACTERIZATION OF OVOKININ, A BRADYKININ B-1 AGONIST PEPTIDE DERIVED FROM OVALBUMIN

A vasorelaxing peptide was purified from a peptic digest of ovalbumin, after three steps of reverse-phase HPLC. The structure of the peptide was Phe-Arg-Ala-Asp-His-Pro-Phe-Leu, which corresponded to residues 358-365 of ovalbumin. The peptide was named ovokinin. Ovokinin showed relaxing activity for a canine mesenteric artery (EC(50) = 6.3 mu M). The relaxing activity was blocked by the bradykinin B-1 antagonist [des-Arg(9)][Leu(8)]bradykinin, but not by the B-2 antagonist Hoe 140. Ovokinin binds to B-1 receptors (IC50 = 64 mu M). Prostaglandin I-2 was released from the artery after ovokinin stimulation as a relaxing factor. Thus, ovokinin is a weak bradykinin B-1 agonist peptide derived from food proteins.