Antigen fractions and proteins
(A) Schematic illustration of the preparation of Yersinia antigenic fractions and single proteins. Using differential centrifugation, three major fractions were obtained from disintegrated Yersinia: membrane fraction, cytoplasmatic proteins, and ribosomal pellet. Acetic acid extraction of the latter, followed by cation exchange chromatography, resulted in purification of the urease β-subunit, the ribosomal protein L23, and a fraction, composed of anionic and neutral proteins (ANP). UC: ultracentrifugation. (B) Elution profile of ribosomal pellet proteins from cation exchange chromatography. A protein fraction without affinity elutes at first and is composed of anionic and neutral proteins (ANP). The urease β-subunit (Uβ) and ribosomal protein L23 are strongly cationic and elute under high molarity conditions. (C) SDS-PAGE under reducing conditions showing the protein content of the ribosomal pellet after acid extraction and the protein peaks obtained by cation exchange chromatography as illustrated in Fig. 1B.