ELECTROPHORETIC SEPARATION OF CONSTITUENTS OF PARTIALLY PURIFIED M PROTEIN OF STREPTOCOCCUS PYOGENES

EFFECT OF PARTIALLY PURIFIED STREPTOCOCCAL M PROTEIN ON THE IN VITRO PHAGOCYTOSIS OF STREPTOCOCCUS PYOGENES

Domingue, Gerald J. (Tulane University, New Orleans, La.), and William A. Pierce, Jr. Effect of partially purified streptococcal M protein on the in vitro phagocytosis of Streptococcus pyogenes. J. Bacteriol. 89:583-588. 1965.-M protein from Streptococcus pyogenes strain Bailey type 12 was adsorbed onto cells of a glossy mutant of this strain. Phagocytosis experiments were performed in vitro with rabbit peritoneal polymorphonuclear leukocytes. Direct microscopic counts suggested M protein-treated cells were more resistant to phagocytosis than were untreated cells. With the Cohn and Morse technique for evaluating quantitatively the fate of bacteria during phagocytosis, there was observed a more rapid drop in total and extracellular counts of treated, as compared with untreated, cells. Experiments with radioactively labeled streptococci showed that M-treated cells were more readily destroyed within leukocytes than were nontreated glossy streptococci, which suggested a reason for the scarcity of treated streptococci in direct microscopic counts.

Chemistry and end-group analysis on purified M protein of type 12 group A streptococcal cell walls

M protein was extracted from the cell walls of streptococci by use of both acidic and alkaline buffers. These extracts were further purified by ammonium sulfate fractionation and column chromatography. Both diethylaminoethyl and carboxymethyl celluloses were employed to cover the pH range of 3.0 to 9.0. All of the M proteins isolated were immunologically related, but their physical and chemical properties varied dependent upon the pH range of isolation. Each isolate appeared to be homogeneous on the basis of immunodiffusion analysis, electrophoretic mobility, and ultracentrifugal analysis, but their amino acid analyses differed slightly. Two factors were shared by all isolates: (i) they all reacted with type-specific antisera and (ii) each seemed to have l-lysine as a single N-terminal amino acid.