Peptic digestion of streptococcal M protein. II. Extraction of M antigen from group A streptococci with pepsin. 1974

E H Beachey, and G L Campbell, and I Ofek

M protein of group A streptococci was extracted by mild peptic digestion. Optimal amounts of type-specific M protein were released after 20 min of digestion with 0.02 mg of pepsin per ml at pH 5.8. Immunological analysis revealed that, unlike conventional HCl extracts, pepsin extracts lacked the surface C carbohydrate antigen and contained less non-type-specific, heat-stable cellular antigens; they also lacked detectable heat-labile T protein. Similar to HCl extracts, however, the pepsin-extracted M protein precipitated homologous-type M antisera and inhibited type-specific opsonization of homologous group A streptococci. Furthermore, the pepsin extract was capable of inducing type-specific opsonic M antibody in rabbits. This method may provide a useful initial step in the purification of M protein by reducing contaminating antigens.

UI MeSH Term Description Entries
D007106 Immune Sera Serum that contains antibodies. It is obtained from an animal that has been immunized either by ANTIGEN injection or infection with microorganisms containing the antigen. Antisera,Immune Serums,Sera, Immune,Serums, Immune
D007114 Immunization Deliberate stimulation of the host's immune response. ACTIVE IMMUNIZATION involves administration of ANTIGENS or IMMUNOLOGIC ADJUVANTS. PASSIVE IMMUNIZATION involves administration of IMMUNE SERA or LYMPHOCYTES or their extracts (e.g., transfer factor, immune RNA) or transplantation of immunocompetent cell producing tissue (thymus or bone marrow). Immunologic Stimulation,Immunostimulation,Sensitization, Immunologic,Variolation,Immunologic Sensitization,Immunological Stimulation,Sensitization, Immunological,Stimulation, Immunologic,Immunizations,Immunological Sensitization,Immunological Sensitizations,Immunological Stimulations,Sensitizations, Immunological,Stimulation, Immunological,Stimulations, Immunological,Variolations
D008722 Methods A series of steps taken in order to conduct research. Techniques,Methodological Studies,Methodological Study,Procedures,Studies, Methodological,Study, Methodological,Method,Procedure,Technique
D009895 Opsonin Proteins Proteins that bind to particles and cells to increase susceptibility to PHAGOCYTOSIS, especially ANTIBODIES bound to EPITOPES that attach to FC RECEPTORS. COMPLEMENT C3B may also participate. Opsonin,Opsonin Protein,Opsonins,Protein, Opsonin
D010434 Pepsin A Formed from pig pepsinogen by cleavage of one peptide bond. The enzyme is a single polypeptide chain and is inhibited by methyl 2-diaazoacetamidohexanoate. It cleaves peptides preferentially at the carbonyl linkages of phenylalanine or leucine and acts as the principal digestive enzyme of gastric juice. Pepsin,Pepsin 1,Pepsin 3
D011817 Rabbits A burrowing plant-eating mammal with hind limbs that are longer than its fore limbs. It belongs to the family Leporidae of the order Lagomorpha, and in contrast to hares, possesses 22 instead of 24 pairs of chromosomes. Belgian Hare,New Zealand Rabbit,New Zealand Rabbits,New Zealand White Rabbit,Rabbit,Rabbit, Domestic,Chinchilla Rabbits,NZW Rabbits,New Zealand White Rabbits,Oryctolagus cuniculus,Chinchilla Rabbit,Domestic Rabbit,Domestic Rabbits,Hare, Belgian,NZW Rabbit,Rabbit, Chinchilla,Rabbit, NZW,Rabbit, New Zealand,Rabbits, Chinchilla,Rabbits, Domestic,Rabbits, NZW,Rabbits, New Zealand,Zealand Rabbit, New,Zealand Rabbits, New,cuniculus, Oryctolagus
D003168 Complement Fixation Tests Serologic tests based on inactivation of complement by the antigen-antibody complex (stage 1). Binding of free complement can be visualized by addition of a second antigen-antibody system such as red cells and appropriate red cell antibody (hemolysin) requiring complement for its completion (stage 2). Failure of the red cells to lyse indicates that a specific antigen-antibody reaction has taken place in stage 1. If red cells lyse, free complement is present indicating no antigen-antibody reaction occurred in stage 1. Complement Absorption Test, Conglutinating,Conglutination Reaction,Conglutinating Complement Absorption Test,Complement Fixation Test,Conglutination Reactions,Fixation Test, Complement,Fixation Tests, Complement,Reaction, Conglutination,Reactions, Conglutination,Test, Complement Fixation,Tests, Complement Fixation
D005779 Immunodiffusion Technique involving the diffusion of antigen or antibody through a semisolid medium, usually agar or agarose gel, with the result being a precipitin reaction. Gel Diffusion Tests,Diffusion Test, Gel,Diffusion Tests, Gel,Gel Diffusion Test,Immunodiffusions,Test, Gel Diffusion,Tests, Gel Diffusion
D006386 Hemagglutination Tests Sensitive tests to measure certain antigens, antibodies, or viruses, using their ability to agglutinate certain erythrocytes. (From Stedman, 26th ed) Hemagglutination Test,Test, Hemagglutination,Tests, Hemagglutination
D000372 Agglutination Tests Tests that are dependent on the clumping of cells, microorganisms, or particles when mixed with specific antiserum. (From Stedman, 26th ed) Agglutination Test,Test, Agglutination,Tests, Agglutination

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