Abstract
A low-molecular-weight proteinase inhibitor was isolated from healthy human plasma. After diafiltration using an Amicon YM 5 membrane, human plasma were concentrated by an Amicon YM 2 membrane. And then samples were chromatographed on a Sephadex G-25 column. After fractions of inhibitory activity against papain were pooled, they were passed through CM Cellulofine. The eluate was then transferred onto a DEAE Cellulofine column. The column was eluted with 200-ml linear gradient of NaCI. Tubes containing inhibitory activity were concentrated and rechromatographed on a Sephadex G-25 column. The isolated fraction showed a single band on 15 % polyacrylamide gel electrophoresis at pH 9.4, and inhibitory activity against papain and trypsin was detected in the band. Approximately 5μg of the isolated inhibitor caused a 50 % inhibition of 5μg papain, and 5μg resulted in a 50 % inhibition of 5μg of trypsin. The molecular weight of the inhibitor was estimated to be approximately 3, 200 daltons by the gelfiltration on Sephadex G-25.
