title: Purification and immunochemical properties of a protein antigen from serotype g Streptococcus mutans.
abstract: A proteinaceous antigen (PAg) was purified from the culture supernatant of Streptococcus mutans 6715 (serotype g) by ultrafiltration, ammonium sulfate precipitation, DEAE-Sephacel ion-exchange chromatography, Phenyl-Sepharose CL-4B hydrophobic chromatography, and subsequent Sephacryl S-300 gel filtration. A yield of 0.1 mg of PAg was obtained from a liter of culture supernatant. The isoelectric point and molecular weight of PAg were pH 4.6 and 210,000, respectively. It contained 35% sugar, which was identified as glucose by gas-liquid chromatography. Amino acid analysis revealed that PAg contains 28% acidic and 11% basic amino acid residues. PAg retained its antigenicity after heating at 80 C for 10 min in deionized water, or after treatment with 0.1 M HC1 or 0.1 M NaOH at 37 C for 1 hr. Immunodiffusion and immunoelectrophoresis analyses revealed that PAg is serologically distinct from other cell-surface antigens such as serotype-specific polysaccharide and lipoteichoic acid. A cross-reaction between PAg and a protein antigen similarly prepared from serotype c S. mutans was observed in immunodiffusion tests.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000942:Antigens, Bacterial / Q000032:analysis / Q000276:immunology / Q000302:isolation & purification*; D001426:Bacterial Proteins / Q000032:analysis / Q000276:immunology / Q000302:isolation & purification*; D011232:Chemical Precipitation; D002850:Chromatography, Gel; D003429:Cross Reactions; D004591:Electrophoresis, Polyacrylamide Gel; D005947:Glucose / Q000032:analysis; D006358:Hot Temperature; D005779:Immunodiffusion; D007122:Immunoelectrophoresis; D007526:Isoelectric Point; D008970:Molecular Weight; D013295:Streptococcus mutans / Q000276:immunology*; D014462:Ultrafiltration
chemical_list: D000596:Amino Acids; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D005947:Glucose