[Purification and characterization of protease inhibitors from urine during pregnancy (author's transl)].

Two forms of urinary trypsin inhibitor, A and B, were purified from the pooled urine from pregnant women using non-denaturing methods. The inhibitor B arose from the inhibitor A and was not present in native urine. Electrophoresis on polyacrylamide gel in the presence of sodium dodecyl sulfate indicated a new heterogeneity of the inhibitor B with molecular weights of 33 000 and 24 000; the molecular weight obtained for the inhibitor A was 50 000. Inhibitors A and B were acidic proteins with an isoelectric pH of about 2.6 for A and about 4.2 for B. Inhibitor A and inter-alpha-trypsin inhibitor formed a precipitate with an antiserum to purified inhibitor B. But neither inhibitor A nor inhibitor B formed a precipitate with anti whole human serum or anti-inter-alpha-trypsin inhibitor antiserum. Measurements of specific activity of inhibitor A were consistent with two active sites in the molecule.