Method of purification of thiol proteinase inhibitors from human urine.

Urinary thiol proteinase inhibitors (UTPI) had been isolated from their complex with papain. Almost 90% of these inhibitors, previously inactivated by native or immobilized papain, were recovered after heating the complex to 80 degrees C at pH 2.0 for 20 min. Two protein inhibitors with molecular weights of 76,000 (UTPI-76) and about 45,000 (UTPI-45) were isolated from urine of patients with malignant colorectal tumor. UTPI-fraction consisted of about 40% of UTPI-76 (probably light form of kininogen) and of 60% of UTPI-45 fraction. The inhibitors differed in affinity to Concanavalin A. No electrophoretic mobility changes of both UTPI, before and after isolation by described affinity chromatography were observed.