抄録
The mode of inhibition of proteolytic enzymes of different origins (animal, plant, and bacteria) and of different groups (serine and cysteine enzymes) by human serum proteinase inhibitors was investigated. The inhibitors which interacted with these enzymes were identified by suppressing their inhibitory actions on these proteolytic enzymes, using monospecific antibodies against the individual serum proteins. The inhibitor α1-antitrypsin predominantly inhibited the serine enzymes of animal origin trypsin [EC 3. 4. 4. 4] and chymotrypsin [EC 3. 4. 4. 5], and had less effect on the serine enzyme of bacterial origin nagarse (subtilisin BPN') [EC 3. 4. 4. 16], and no inhibitory effect on the enzymes of plant origin papain [EC 3. 4. 4. 10], ficin [EC 3. 4. 4. 12], and stem bromelain [EC 3. 4. 4. 24]. In contrast α2-macroglobulin inhibited all kinds of proteolytic enzymes irrespective of their enzyme groups or origins. From these it is concluded that 1) serum proteinase inhibitors have the potentiality to inhibit foreign proteolytic enzymes, 2) α1-antitrypsin seems to have a fairly broad specificity for serine enzymes of animal origin and of other origins, and 3) α2-macroglobulin can combine with both serine and cysteine enzymes, regardless of the stereospecificities of their active sites.
