Hydrolysis of rat high molecular weight kininogen by purified rat urinary kallikrein: identification of bradykinin as the kinin formed.

We have previously reported that, although human urinary kallikrein, like glandular kallikreins for other species, releases lysyl-bradykinin from homologous and heterologous substrates, rat urinary kallikrein released a kinin which migrated like bradykinin in CM-cellulose chromatography and polyacrylamide gel electrophoresis (BBA677, 471, 1981). In the study we definitively established the nature of the kinin produced by rat urinary kallikrein by using purified enzyme and substrate, HPLC, radioimmunoassay and N-terminal analysis. Rat urinary kallikrein was purified to apparent homogeneity by a procedure which included affinity chromatography on aprotinin agarose. The kinin produced by rat urinary kallikrein acting on either pure rat high molecular weight kininogen or rat plasma or semipurified bovine and dog plasma was identified as bradykinin. This observation provides the evidence of species differences in the specificity of glandular kallikreins acting on kininogens.