[Effective method of isolating an acid-stable protease inhibitor from human urine].

A modification is described of the previously developed procedure for isolation of acid stable proteinase inhibitor (ASI) from urine of patients with nephritis. The modified procedure enabled to increase the yield of the inhibitor and to obtain its highly purified preparations. These preparations possessed a property to inhibit effectively the activity of human granulocyte elastase (ki = 10(4) M-1 min-1). The modified procedure is based on affinity chromatography on chymotrypsin-Sepharose 4B, substitution of dialysis by gel filtration on Sephadex G-25, use of alternative methods for concentration of protein fractions instead of membrane ultrafiltration and chromatography on polyamide for ASI depigmentation. The inhibitor yield amounted up to 75% of the initial activity in urine. The possibilities of the human urine ASI use in medical practice are discussed.