Generation of .ALPHA.- and .BETA.-kallikreins from porcine pancreatic prokallikrein by the action of trypsin.

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Abstract
Prokallikrein was activated into .alpha.-kallikrein (single polypeptide chain) by the action of trypsin and further converted to .beta.-kallikrein (two polypeptide chains) as indicated by the following observations; 1) When prokallikrein was activated with trypsin, rapid generation of kallikrein activity was observed followed by a slow decrease in the kallikrein activity during prolonged incubation. The same phenomenon of the slow decrease in the activity of .alpha.-kallikrein separately isolated was also observed on trypsin treatment. 2) From the results of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), the kallikrein which was rapidly generated from prokallikrein by the action of trypsin was .alpha.-kallikrein. And the kallikrein obtained from .alpha.-kallikrein by further treatment with trypsin was .beta.-kallikrein. 3) The N-terminal amino acid of .alpha.-kallikrein was isoleucine. In the case of .beta.-kallikrein, two amino acids, isoleucine and alanine, were detected as N-terminal amino acids. Conversion of .alpha.-kallikrein to .beta.-kallikrein by the action of trypsin caused a decrease of N.alpha.-benzoyl-L-arginine ethyl ester (Bz-Arg-OEt) hydrolyzing activity and changes of the kinetic constants for the hydrolysis of Bz-Arg-OEt. The kinetic constants of this .beta.-kallikrein were distinctly different from those of the .beta.-kallikrein obtained from autolyzed pancreas. The above observation suggested that the .beta.-kallikrein obtained in the present paper was a different type of .beta.-kallikrein from that obtained from autolyzed pancreas.