The isolation of bradykinin, a plasma kinin from ox blood

Abstract
Bradykinin was formed by trypsin digestion of the fraction of ox serum proteins which precipitated between 33 and 45% of saturation with ammonium sulphate. Bradykinin was isolated in the pure state by application of the techniques of countercurrent distribution, chromato-graphy on carboxymethylcellulose and paper electrophoresis. Bradykinin contained the five amino acids glycine, serine, proline, phenyl-alanine and arginine in the molar proportions 11:3:2:2 and one of the arginine residues was N-terminal.