Isolation and characterization of two minor fractions of alpha 1-antitrypsin by high-performance liquid chromatographic chromatofocusing.

alpha 1-Antitrypsin is a glycoprotein that separates into five electrophoretic fractions, viz. M2, M4, M6, M7 and M8. Con A-Sepharose separates the protein into three fractions according to the branching degree of the three oligosaccharide chains. The Con A affinity is identical for M4 and M7 and for M6 and M8. Within each pair the proteins were isolated by rapid chromatofocusing. The M7 and M8 have the same carbohydrate structure as the major M4 and M6 respectively, but have lost the first five N-terminal amino acids (Glu-Asp-Pro-Glu-Gly) as compared to the majority of the protein.