Abstract
Porcine pancreatic kallikreins generated from their precursors"prokallikreins A and B"in three different ways, i.e., (1) kallikreins A and B obtained from autolyzed pancreas, (2) kallikreins A'and B'spontaneously generated during the purification of prokallikreins A and B and (3) kallikreins A"and B"generated from purified prokallikreins A and B by treatment with trypsin, were each highly purified and their properties were compared. The Km values for BzArgOEt hydrolysis, the mobilities on immunoelectrophoresis and the elution profiles from a DEAE-Sepharose CL-6B column of kallikreins A'and B'and kallikreins A"and B"closely resembled each other but apparently differed from those of kallikreins A and B. Kallikreins A and B were confirmed to consist of two polypeptide chains (three chains to some extent), while kallikreins A", B"and B'were each determined to consist of a single chain. The amino acid compositions of the two-chain kallikrein and the single-chain kallikrein were very similar, though somewhat higher values of Leu, Glu and Lys residues were observed in the single-chain kallikrein as compared with the two-chain kallikrein. Thus, kallikreins A"and B"generated from prokallikreins A and B by the action of trypsin were considered to be very similar to, or identical with, kallikreins A'and B'spontaneously generated during the purification of prokallikreins A and B. It is speculated that two-chain kallikreins A and B are generated from single-chain kallikreins A"and B"by the action of some protease (s) other than trypsin during the autolysis process.
