-antiplasmin (al´fә an″tĭ-plaz´min) see antiplasmin.-macroglobulin (al´fә mak´ro-glob″u-lin) α2-macroglobulin a plasma protein that inhibits a wide variety of proteolytic enzymes, including trypsin, plasmin, thrombin, kallikrein, and chymotrypsin, by entrapping and reducing the accessibility of their functional sites to large molecules.