The interaction of alpha-1-antitrypsin with soluble and sepharose-bound elastase

The products resulting from the interaction of alpha-1-antitrypsin with elastase were examined with polyacrylamide gel electrophoresis in the presence and absence of sodium dodecyl sulfate, and by affinity chromatography. Five products of the reaction can be identified by polyacrylamide disc gel electrophoresis. Two products are complexes between alpha-1-antitrypsin and elastase (73 800 and 58 300 daltons). Two additional products are identical to fragments of alpha-1-antitrypsin which can be washed from a column of Sepharose-bound elastase immediately after alpha-1-antitrypsin is applied to the column. The larger component about 50 000 daltons, reacts with antiserum to alpha-1-antitrypsin, and does not inhibit enzymes. Together, these two products have an amino acid analysis similar to alpha-1-antitrypsin. These two fragments are probably hydrolytic products of the interaction of elastase with alpha-1-antitrypsin which is biologically inactive. The fifth product is probably a fragment of alpha-1-antitrypsin missing from the low molecular weight complex. The components of the complexes can be separated from each other by a mild nucleophilic attack. Small quantities of alpha-1-antitrypsin can be displaced from the elastase affinity column by phenyl methane sulfonyl fluoride. In conclusion, porcine pancreatic elastase forms two complexes with alpha-1-antitrypsin. One or both complexes can be split by alkali.