Conversion of rat urinary prokallikrein to its active form

A peptide derived from rat urinary prokallikrein by trypsin treatment comprised 7 amino acids, the sequence (Ala-Pro-Pro-Val-Gln-Ser-Arg) of which was identical with that of the N-terminal region in prokallikrein. Thus, with trypsin treatment, rat urinary prokallikrein is converted to the active form with the release of the N-terminal propeptide consisting of 7 amino acids. An Arg-1-Val+1 bond in the prokallikrein was found to be the site of proteolytic cleavage of the propeptide.