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Extraction of streptococcal type 12 M protein by cyanogen bromide
Abstract:
Conditions for the release of streptococcal type 12 M protein from whole cells by cyanogen bromide are described; they demonstrated that methionine is not essential to the structural arrangements which account for some of its immunological and biological properties. The released M protein was separated from other proteins by column chromatography with hydroxylapatite. The type-specific molecules which reacted with precipitating antibodies were found only in the 0.3 M eluate, formed zones with mobilities less than 12% of that of the dye front on electrophoresis in the standard acrylamide disc gel system, formed at least four bands in sodium dodecyl sulfate-acrylamide disc gels with molecular weights ranging from 12,000 to 23,000, and stimulated the formation of opsonic antibodies in rabbits. Cyanogen bromide provides a highly specific method for the release of M proteins which should prove particularly useful in analyses of structural-functional relationships among different M proteins.
Insights
Streptococcal type 12 M protein release using cyanogen bromide shows methionine is not essential for its properties. This method aids in analyzing M protein structure-function relationships.
Area of Science:
- Microbiology
- Immunology
- Biochemistry
Background:
- Streptococcal M proteins are crucial virulence factors.
- Understanding M protein structure is key to developing vaccines and therapeutics.
- Specific methods for M protein isolation are needed.
Purpose of the Study:
- To describe conditions for releasing streptococcal type 12 M protein using cyanogen bromide.
- To investigate the role of methionine in M protein structure and function.
- To characterize the isolated M protein and its immunological properties.
Main Methods:
- Release of M protein from whole cells using cyanogen bromide.
- Separation of M protein by hydroxylapatite column chromatography.
- Electrophoresis in acrylamide disc gels and SDS-acrylamide disc gels for characterization.
Main Results:
- Methionine is not essential for key immunological and biological properties of M protein.
- Type-specific M protein was isolated in the 0.3 M eluate.
- Electrophoretic analysis revealed distinct M protein bands with molecular weights from 12,000 to 23,000.
- The isolated M protein stimulated opsonic antibody formation in rabbits.
Conclusions:
- Cyanogen bromide is a specific method for releasing M proteins.
- This technique facilitates structural-functional analyses of M proteins.
- The findings contribute to understanding streptococcal virulence and immunity.