title: Inhibitors of acrosin and granulocyte proteinases from human genital tract secretions.
abstract: Human seminal plasma contains two acid-stable proteinase inhibitors, HUSI-II (Mr approximately 6500) and HUSI-I, (Mr approximately 11 000) with different inhibition specificities. The inhibitory activity of HUSI-II is strongly limited to trypsin and acrosin; both enzyme-inhibitor complexes are very stable (e.g. bovine trypsin-HUSI-II complex: Ki = 1 x 10(-10)M; human acrosin-HUSI-II complex: Ki = 2.7 x 10(-10)M). The inhibitor from human seminal plasma HUSI-II may therefore be seen as the natural antagonist of the sperm protease acrosin. In addition to pancreatic trypsin and alpha-chymotrypsin, HUSI-I forms strong complexes with neutral proteases of the lysosome-like granules from human granulocytes, for example, the elastase (Ki = 2.5 x 10(-9)M) and cathepsin G, the chymotrypsin like protease (Ki = 7 x 10(-8)M).
mesh_terms: D000176:Acrosin / Q000037:antagonists & inhibitors*; D000818:Animals; D002403:Cathepsins / Q000037:antagonists & inhibitors; D002417:Cattle; D002582:Cervix Mucus / Q000032:analysis; D002918:Chymotrypsin / Q000037:antagonists & inhibitors; D004285:Dogs; D005260:Female; D005835:Genitalia / Q000378:metabolism*; D006098:Granulocytes / Q000201:enzymology*; D006801:Humans; D007962:Leukocytes / Q000201:enzymology*; D008297:Male; D010196:Pancreatic Elastase / Q000037:antagonists & inhibitors; D011480:Protease Inhibitors; D012661:Semen / Q000032:analysis; D013552:Swine; D014361:Trypsin Inhibitors / Q000302:isolation & purification
chemical_list: D011480:Protease Inhibitors; D014361:Trypsin Inhibitors; D002403:Cathepsins; D002918:Chymotrypsin; D000176:Acrosin; D010196:Pancreatic Elastase