Isolations of protein A and protein G from the bacterial surface.
Ten tested cultures each of Staphylococcus aureus (S. aureus) and of Streptococcus belonging to serological group G bound human IgG to a high extent. Protein A could be solubilized from strain Cowan I of S. aureus by lysozyme, mutanolysine, hydroxylammoniumchloride, hot acid extraction or lysostaphin and subsequently purified by affinity chromatography on human IgG-sepharose. The purified protein A preparation had molecular weights between 29,000 and 63,000 D and inhibited binding of 125I-labeled human IgG to S. aureus Cowan I. Protein G could be solubilized from strain 26540 of the G-streptococci with lysozyme or hot acid extraction and purified by affinity chromatography on human IgG-sepharose. The purified protein G revealed a molecular weight of 67,000 D and inhibited binding of human IgG to the G-streptococci.
Institut für Bakteriologie und Immunologie, Justus-Liebig-Universität Giessen.
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Sting
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Lauerman
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Blobel
D001426:Bacterial Proteins / Q000302:isolation & purification*; D002846:Chromatography, Affinity; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism*; D008970:Molecular Weight; D012995:Solubility; D013205:Staphylococcal Protein A / Q000302:isolation & purification*; D013211:Staphylococcus aureus / Q000032:analysis*; D013291:Streptococcus / Q000032:analysis*
D001426:Bacterial Proteins; C034284:IgG Fc-binding protein, Streptococcus; D007074:Immunoglobulin G; D013205:Staphylococcal Protein A