Abstract
The interactions of mouse murinoglobulin and α-macroglobulin with several proteinases were investigated by gel filtration and by assays of amidolytic activity towards synthetic substrates in the presence of proteinaceous enzyme inhibitors as well as assays of the inhibition of proteolytic activity. Mouse α-macroglobulin formed complexes with thrombin, clotting factor Xa, plasmin, pancreatic kallikrein, plasma kallikrein, submaxillary gland trypsin-like proteinase, neutrophil elastase, and pancreatic elastase. These complexes lost the proteolytic activities against high-molecular-weight substrates, but protected the active sites of the enzymes from inactivation by their proteinaceous inhibitors. Mouse murinoglobulin showed essentially the same properties except (i) that it did not form a complex with the clotting factor Xa, and (ii) that it did not protect plasma kallikrein, neutrophil elastase or submaxillary proteinase from inactivation by their proteinaceous inhibitors, although it formed complexs with these proteinases. No interaction was detected between Clostridium histolyticum collagenase and murinoglobulin or α-macroglobulin. These results indicate (i) that murinoglobulin has a proteinase-binding spectrum similar to that of α-macroglobulin, but is weaker in the ability to protect the bound proteinases from inactivation by the proteinaceous inhibitors than α-macroglobulin and (ii) that mouse α-macroglobulin has essentially the same inhibitory spectrum as the human homologue.
