| Popis: |
There is growing evidence for functionally different kininogens in the same animal plasma. Fractionation of plasma may cause loss of especially susceptible kininogens. We tried to find out whether the kininogens of bovine serum differ by their primary structure. Whole, unfractionated serum has been digested with pepsin and the peptide mixture separated by the following steps: 1. distribution between isopropanol-ether and water; 2. treatment with isopropanol-petrolether; 3. gel filtration on sephadex G 25; 4. chromatography on carboxymethyl cellulose; 5. chromatography on phosphorylated cellulose; 6. paper chromatography [n-butanol (15)—pyridin (10)—acetic acid (3)—water (12)]; 7. high voltage paper electrophoresis. Two peptide fractions have been distinguished by step 6. The main peptide, finally purified by step 7, yielded 14 residues on amino acid analysis: lys (1), arg (2), ser (2), glu (1), pro (3), gly (1), val (1), met (1), phe (2). Position 1–10 has been elucidated by Edman degradation (direct method). The peptide was resistent against carboxy-peptidase B; it released kinin activity not only with trypsin and pancreatic kallikrein but also with carboxypeptidase A. Thus the general structure met-lys-(bradykinin)-(ser, val, glx) has been established, in accordance with the peptide previously isolated from peptic digest of purified bovine kininogen [1]. Bradykinin is released by high amounts of trypsin, met-lys-bradykinin by low trypsin concentrations and by pancreatic kallikrein and carboxypeptidase A. |
