Isolation and properties of two rat plasma T-kininogens.

Two species of T-kininogen which release T-kinin (Ile-Ser-bradykinin) have been purified from plasma of rats treated with Freund's complete adjuvant. The molecular weight was estimated to be 69,000 for either T-kininogen I and II by SDS-polyacrylamide gel electrophoresis. Trypsin released one mole of T-kinin from one mole of either T-kininogen, but glandular kallikrein, including rat urinary and rat submandibular gland kallikreins and human urinary kallikrein, did not release any kinin from T-kininogens. Cathepsin D, which was purified from rat liver, released T-kinin from T-kininogens at pH 4.0. These results indicate that rat plasma contains two types of T-kininogen which differ from high molecular weight and low molecular weight kininogens.