Isolation and partial characterization of rat α 1 ‐antitrypsin

α 1 ‐Antitrypsin was isolated from rat serum by salting out with ammonium sulfate in three steps, followed by repeated ion exchange on DEAE‐Sephadex A 50 and affinity chromatography on Affi‐Gel Blue. The fractionation was paced with isoelectric focusing in polyacrylamide gels with pH range 3.5‐9.5. The resultant protein was homogeneous in crossed immunoelectrophoresis using rabbit antiserum against whole rat serum. Isoelectric focusing in α 1 ‐antitrypsin phenotyping plates with pH range 4–5 showed a clear five‐band pattern of isolated protein (isoelectric points 4.41, 4.48, 4.50, 4.58 and 4.61, respectively). Immunofixation and zymogram techniques were used to identify the α 1 ‐antitrypsin bands. In sodium dodecyl sulfate/polyacrylamide gel electrophoresis two bands appeared. They had relative mobilities corresponding to apparent molecular weights of 50 000 and 56 000.