title: Multiple molecular forms of acid-stable plasmin inhibitor derived from human urinary trypsin inhibitor.
abstract: It was found that cyanogen bromide (BrCN) treatment of the highly purified human urinary trypsin inhibitors (H-UTI; specific activity 1,897 U/mg protein, and L-UTI; specific activity 1,850 U/mg protein) readily produced new plasmin inhibitors with almost no loss of UTI activity. Five multiple forms of chemically cleaved inhibitors (UTIB-I, UTIB-II, UTIB-III, UTIB-IV and UTIB-V) could be isolated from BrCN-treated L-UTI by isoelectric focusing and gel filtration. These inhibitors were very acid-stable and their isoelectric points (pI) were 4.5, 4.6, 4.9, 5.1 and 6.4, respectively. The molecular weights by SDS-polyacrylamide gel electrophoresis were almost the same at about 23,000 +/- 3,000. Although these inhibitors showed both anti-plasmin and anti-trypsin activities, much higher anti-plasmin/anti-trypsin activities were observed in the cleaved inhibitors than in the parent UTI. They competitively inhibited human plasmin with Ki values of 3.0-4.1 X 10(-8) mol/l (H-D-Val-Leu-Lys-pNA substrate).
mesh_terms: D000933:Antifibrinolytic Agents / Q000302:isolation & purification*; D003488:Cyanogen Bromide; D004355:Drug Stability; D004591:Electrophoresis, Polyacrylamide Gel; D006023:Glycoproteins / Q000032:analysis*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis; D014361:Trypsin Inhibitors / Q000652:urine*
chemical_list: D000933:Antifibrinolytic Agents; D006023:Glycoproteins; D010446:Peptide Fragments; D014361:Trypsin Inhibitors; C028665:urinastatin; D003488:Cyanogen Bromide