title: Comparison of gel filtration and ammonium sulphate precipitation in the purification of diphtheria toxin and toxoid.
abstract: Crude diphtheria toxin and toxoid were subjected to purification by gel filtration and stepwise ammonium sulphate precipitation. The various fractions obtained by the purification procedures were studied by immunological methods. A high molecular weight fraction of glycoprotein nature was present in all of the crude preparations studied. The fraction was antigenically non-identical with the real toxin or toxoid and did not have its origin in the culture medium. It showed a long flocculation time when tested against equine diphtheria toxoid antiserum. The fraction could be removed from the crude preparations by gel filtration or by precipitation with 21% (w/v) ammonium sulphate. When comparing toxoids purified by each of these methods, the method of gel filtration resulted in a somewhat higher degree of purity, suggesting that this method would be more suitable than the AS precipitation method for the purification of diphtheria toxoid.
mesh_terms: D000645:Ammonium Sulfate; D000937:Antigen-Antibody Reactions; D011232:Chemical Precipitation; D002850:Chromatography, Gel; D004167:Diphtheria Toxin / Q000276:immunology / Q000302:isolation & purification*; D004168:Diphtheria Toxoid / Q000276:immunology / Q000302:isolation & purification*; D004591:Electrophoresis, Polyacrylamide Gel; D007122:Immunoelectrophoresis; D007123:Immunoelectrophoresis, Two-Dimensional
chemical_list: D004167:Diphtheria Toxin; D004168:Diphtheria Toxoid; D000645:Ammonium Sulfate