On the various forms of the glandular kallikrein from autolyzed porcine pancreas.

Kallikrein C, a minor form of the glandular kallikrein isolated form autolyzed porcine pancreas, has the same amino acid composition a porcine pancreatic beta-kallikreins A and B and comparable specific activity, but a much lower carbohydrate content. Dodecyl sulfate electrophoresis of the reduced enzyme indicated that it is composed of the same two polypeptide chains as the other pancreatic beta-kallikreins of the pig. The carbohydrate content of the two chains of beta-kallikrein B has been determined. Both the A and the B chain of beta-kallikreins from autolyzed porcine pancreas exist in a high-molecular (h) and a low-molecular (1) form which evidently differ only in their carbohydrate content. beta-Kallikrein B has the composition AhBh, beta-kallikrein A, AhB1, and beta-kallikrein C, A1B1. The properties of kallikrein III from porcine pancreas, recently described by Kira et al. (Adv. Exp. Med. Biol. 120A (1979) 273--290), indicate that is is the fourth conceivable form, A1Bh. A preparation of porcine pancreatic kallikrein d2 was found to have a specific activity comparable to that of other kallikrein preparations. Besides a main component migrating like pancreatic beta-kallikrein A, it also contained beta-kallikreins B and C. All four species of chains were observed to occur in this batch of the enzyme. Zuber and Sache (Biochemistry 13 (1974) 3098--3110) reported the resolution of porcine pancreatic kallikreins d1 and d2 into three electrophoretic components each after reduction. Evidently, all these preparations consist of a mixture of several forms of two-chain pancreatic beta-kallikrein.