The elastase inhibitors of swine serum: isolation and partial characterization of the beta 1-globulin inhibitor and its interaction with elastase.
1. The principal elastase inhibitor of swine serum, a beta 1-globulin, has been isolated from serum by ammonium sulfate fractionation, DEAE-cellulose column chromatography and chromatofocusing. 2. The purified beta 1-globulin was homogeneous by immunoelectrophoresis and sodium dodecyl sulfate polyacrylamide gel electrophoresis. Multiple zones (isoinhibitors) were produced on anionic polyacrylamide gels. The mol. wt for the native, elastase-inactivated inhibitor and the beta 1-globulin-elastase complex were respectively, 65,467 and 60,000 and 79,667. The amino acid residue weight was 63,331. 4. The electrophoretic mobilities of the native inhibitor, elastase-inactivated inhibitor and the inhibitor-elastase complex were respectively, -3.4, -3.8 and -2.2 x 10(-5) cm2/V per sec, the isoelectric points were respectively, 4.78-5.28 (major pIs = 5.15, 5.35), 4.63-5.35 (major pI = 5.13) and 6.02-6.2 (major pI = 6.12). 5. The first order dissociation rate constant for the beta 1-globulin-elastase complex (two-fold molar excess of elastase at 37 degrees C) was 1.9 x 10(-3) per sec with complete dissociation in 40.4 min. The dissociation constant for the complex was 1.47 x 10(-7) M. One mol of elastase was bound per mol of the inhibitor. 6. The beta 1-globulin-elastase complex reacts with antibody to either protein moiety.