title: Evaluation of methods used to purify acid-extracted group A streptococcal M protein.
abstract: The literature includes descriptions of both acid-soluble and acid-insoluble M protein in the preparation of "hot acid-extracted group A streptococcal M protein." We present evidence for the contamination of crude type 1 acid-insoluble M protein. The purification of preparations of crude and partially purified acid-soluble type 1 and type 12 M protein is described. Our quantitative criteria for purification were recovery of M precipitin activity, improvement in specific activity, and removal of carbohydrate. Exclusion of nucleic acid is also discussed. Greater purification in a single passage was found with a carboxymethylcellulose column (with acidic elution) than with hydroxyapatite, diethylaminoethyl-Sephadex, or carboxymethyl-cellulose (with neutral elution) columns or with ammonium sulfate fractional precipitation. Carboxymethylcellulose with acidic elution was found to be a satisfactory standard laboratory procedure for the preparation of purified acid-extracted (acid-soluble) group A streptococcal M protein.
mesh_terms: D011232:Chemical Precipitation; D002852:Chromatography, Ion Exchange; D003470:Culture Media; D005069:Evaluation Studies as Topic; D006358:Hot Temperature; D006851:Hydrochloric Acid; D006863:Hydrogen-Ion Concentration; D006882:Hydroxyapatites; D007106:Immune Sera; D005779:Immunodiffusion; D008722:Methods; D008747:Methylcellulose; D011233:Precipitin Tests; D000644:Quaternary Ammonium Compounds; D012703:Serotyping; D013053:Spectrophotometry; D013297:Streptococcus pyogenes / Q000032:analysis* / Q000254:growth & development / Q000276:immunology; D014461:Ultracentrifugation; D014764:Viral Proteins / Q000302:isolation & purification*
chemical_list: D003470:Culture Media; D006882:Hydroxyapatites; D007106:Immune Sera; D000644:Quaternary Ammonium Compounds; D014764:Viral Proteins; D008747:Methylcellulose; D006851:Hydrochloric Acid