title: Guanidine extraction of streptococcal M protein.
abstract: A new method of extracting M protein from streptococcal cell walls has been presented. The extracting agent was guanidine-hydrochloride, a protein denaturant. The crude guanidine extract was further purified by ammonium sulfate and pH 5 fractionation and by hydroxyapatite column chromatography. Three major protein peaks were eluted from the hydroxyapatite column with 0.01, 0.1 and 0.3 M  phosphate buffer, respectively. Protein fractions eluted at 0.1 and 0.3 M phosphate concentractions contained antigens that precipitated with homologous M-protein specific antisera, whereas the 0.01 M phosphate fraction had no immunological activity. The fraction eluted with 0.3 M phosphate was electrophoretically homogeneous in sodium dodecyl sulfate-acrylamide gels and elicited the production of bactericidal antibodies in rabbits. The 0.1 M phosphate buffer eluant was electrophoretically heterogeneous and did not elicit the production of bactericidal antibodies in rabbits.
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000302:isolation & purification*; D001433:Bacteriolysis; D002473:Cell Wall / Q000276:immunology*; D005591:Chemical Fractionation; D002845:Chromatography; D004591:Electrophoresis, Polyacrylamide Gel; D006146:Guanidines; D006882:Hydroxyapatites; D007106:Immune Sera; D005779:Immunodiffusion; D009895:Opsonin Proteins; D011233:Precipitin Tests; D011817:Rabbits / Q000276:immunology; D012967:Sodium Dodecyl Sulfate; D013297:Streptococcus pyogenes / Q000276:immunology*
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D006146:Guanidines; D006882:Hydroxyapatites; D007106:Immune Sera; D009895:Opsonin Proteins; D012967:Sodium Dodecyl Sulfate