title: Proteinase inhibitors in rat serum. Purification and partial characterization of three functionally distinct trypsin inhibitors.
abstract: Three different serine proteinase inhibitors were isolated from rat serum and purified to apparent homogeneity. One of the inhibitors appears to be homologous to alpha 1-proteinase inhibitor isolated from man and other species, but the other two, designated rat proteinase inhibitor I and rat proteinase inhibitor II, seem to have no human counterpart. alpha 1-Proteinase inhibitor (Mr 55000) inhibits trypsin, chymotrypsin and elastase, the three serine proteinases tested. Rat proteinase inhibitor I (Mr 66000) is active towards trypsin and chymotrypsin, but is inactive towards elastase. Rat proteinase inhibitor II (Mr 65000) is an effective inhibitor of trypsin only. Their contributions to the trypsin-inhibitory capacity of rat serum are about 68, 14 and 18% for alpha 1-proteinase inhibitor, rat proteinase inhibitor I and rat proteinase inhibitor II respectively.
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000302:isolation & purification; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D002918:Chymotrypsin / Q000037:antagonists & inhibitors; D004591:Electrophoresis, Polyacrylamide Gel; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D014361:Trypsin Inhibitors / Q000097:blood* / Q000302:isolation & purification; D000515:alpha 1-Antitrypsin
chemical_list: D001798:Blood Proteins; D014361:Trypsin Inhibitors; D000515:alpha 1-Antitrypsin; C041097:rat proteinase inhibitor I; C041096:rat proteinase inhibitor II; D002918:Chymotrypsin