Isolation of rat submandibula kallikreins by using immunoadsorption chromatography

A one-step immunoadsorption method for the isolation of glandular kallikreins is described using the immunoglobulin fraction from rabbit anti-(rat glandular kallikrein) serum coupled to CNBr-activated Sepharose 4B. The adsorptions of 125I-labelled kallikrein or unlabelled kallifrein from 100 000 g submandibular gland supernatants were more than 97% complete. The elution of kallikrein from the immunoadsorbent using guanidine hydrochloride gave about 20% yield, which could be increased up to 70% by including 0.5% bovine serum albumin in the elution buffer. The electrophoretic mobility of eluted submandibular 125I-labelled kallikrein or submandibular glandular kallikrein was not altered after affinity chromatography, as judged by conventional polyacrylamide disc-gel electrophoresis or by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate. In addition, the specific esterase and the kininogenase activities of isolated submandibular kallikreins were more than 90% of those of the reference enzyme. This procedure, which results in the isolation of immunologically and biologically active submandibular kallikrein, may also be used for purificaton of other glandular kallikreins that show immunological homology.