Intracellular Neutral Proteinases and Their Inhibitors

An endogenous inhibitor of cysteine and serine proteinases from spleen

“…It was already known that these protein isoinhibitors inhibit intracellular proteinases of cysteine and serine type. We had also found that cathepsin D does not inactivate (degrade) sericystatin, whereas it does inactivate other types of intracellular inhibitors, such as the inhibitors of urokinase [17,18] and elastase [17].…”

Isolation and Some Characteristics of Urokinase Inhibitors Isolated from Pig Leucocytes

“…On the basis of the different solu bility of proteinases at low ionic strength, dialysis (against water) caused the pre cipitation of neutral proteinases, while acid proteinases and inhibitors remain soluble (23,29). When the extraction is directed towards the isolation of inhibi tors, another important finding has to be considered, namely, the inactivation of these inhibitors at acid pH, by acid proteinases (21,23). In the present prepara tion of fibrinolytic inhibitors from nuclei all these important points were taken into consideration.…”

“…In our earlier studies we noticed that leuco cyte cytoplasm (post granule supernatant fraction) contains an inhibitor of uro kinase (18) and that cathepsin D inactivates its inhibitory activity (21). In this work we described the isolation procedure of urokinase inhibitors from leucocyte cells, as well as the biochemical characteristics of the larger inhibitor which was obtained in pure form.…”

“…In contrast, however, the urokinase in hibitory activity of the unpurified extract was highly diminished by acid treat ment, from ph 3 to 5. In some of our recent work it was established that cathepsin D irreversibly inactivated urokinase inhibitory activity as well as the elastase inhibitory activity (21).…”

“…In the course of our continuing studies, two types of specific inhibi tors of proteinases were isolated from pig leucocytes and from bovine spleen. These inhibitors are acidic proteins (Ip 4.6-5.6) and differ in molecular weight, inhibitory ability against tested enzymes and immunologically (4,(17)(18)(19)(20)(21). Neither Inhibitor-1 (1-1) nor Inhibitor-2 (1-2) inhibits trypsin or urokinase.…”