Studies on Partial Purification by Affinity Chromatography and Synthetic Inhibitors of Leukocyte Cathepsin G

The research referring to leukocyte cathepsin G (chymotrypsin like proteinase, CLP) is not sufficient compared with that of leukocyte elastase (ELP), and consequently the physiological role is not evident. In order to investigate the physiological role of CLP we devised a simple purification method which is able to separate CLP from ELP. CLP was purified with an affinity column, Suc-L-Tyr-D-Leu-D-Val-pNA-sepharose. CLP in leukocyte extract adsorbed to the column at low concentration of NaCl (0.2M), and was eluted with tris-HCl buffer (0.1M, pH 7.5) containing 2M NaCl. Purified CLP preparation contained no ELP activity. Although the proteolytic activity of CLP against fibrinogen and fibrin was very weak compared with those of ELP, CLP acted synergistically with ELP in the fibrinogenolysis. Furthermore the effect was dependent on the amount of CLP. Inhibitory effect of each eglin c fragments for CLP and ELP was different. Ki values of H-(41-49)-OMe, fragment containing active center of eglin c, were 4×10-5M for CLP and >2×10-3M for ELP. On the other hand, eglin c and H-(8-70)-OMe inhibited CLP and ELP at low concentration. Although the physiological role of CLP is unclear, it was suggested that the proteolysis of CLP might be shown under coexistence of ELP.