Purification and partial characterization of cat pancreatic and urinary kallikreins--comparison with other cat tissue kallikreins and related proteases.

Kallikreins have been purified from cat pancreas and urine by methods similar to those described previously for cat colon and submandibular gland kallikreins. The pancreatic kallikrein (M.W. 41,200, pI 4.75) was similar to the urinary kallikrein (M.W. 34,300 pI 4.35-4.70) in pH optimum, substrate specificity and inhibition profile. Both enzymes were potent kininogenases and immunologically similar. These enzymes closely resembled the kallikreins from cat colon and submandibular glands. A trypsin (M.W. 18,800) was isolated from cat pancreas and shown to be distinct from the group of kallikreins in all parameters tested. We attempted purification of cat renal kallikrein, but were unable to isolate any such enzyme. The major acidic esterase of cat kidney cortex (M.W. 59,000, pI 4.91) was purified and was distinct from both the cat tissue kallikreins and trypsin. The origin of cat urinary kallikrein remains unclear, but in the light of our findings, it may result from renal filtration of blood-borne tissue kallikreins rather than from intrarenal synthesis.