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Type 1 and 3 M-proteins of Streptococcus pyogenes: peptic extraction and fibrinogen binding properties
O Kühnemund1, L Moravek, J Havlicek
1Academy of Sciences of the GDR, Central Institute of Microbiology and Experimental Therapy, Jena.
Abstract:
The pepsin extraction of group A type 1 streptococci for the isolation of M protein fragments was studied at different pH values and at different time intervals. The extracts were compared by SDS PAGE and fused rocket immunoelectrophoresis. Type 1 M protein fragments were prepared in preparative scale by pepsin extraction of type 1 streptococci at pH 5.5 for 60 min. The fragments were separated by affinity chromatography on immobilized fibrinogen and finally purified for sequence studies by gel chromatography. Pepsin extraction of group A type 3 streptococci was also studied at different pH values. In contrast to type 1, the SDS PAGE pattern changed drastically in dependence on the pH. Affinity chromatography on immobilized fibrinogen is also effective in the separation of the pH 5.5 type 3 streptococcal pepsin extract.
Insights
Pepsin extraction effectively isolates streptococcal M protein fragments. Optimized pH and time yield pure fragments for further study, with type 3 M protein showing pH-dependent extraction patterns.
Area of Science:
- Microbiology
- Biochemistry
- Immunology
Background:
- M proteins are crucial virulence factors in Group A Streptococcus.
- Efficient isolation methods are needed for M protein fragment analysis.
- Understanding M protein structure aids in vaccine development and therapeutic strategies.
Purpose of the Study:
- To optimize pepsin extraction conditions for isolating M protein fragments from Group A Streptococcus.
- To characterize M protein fragments from Type 1 and Type 3 strains.
- To evaluate purification techniques for M protein fragments.
Main Methods:
- Pepsin extraction of streptococci at varying pH and time intervals.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for fragment analysis.
- Fused rocket immunoelectrophoresis for protein characterization.
- Affinity chromatography on immobilized fibrinogen for separation.
- Gel chromatography for final purification.
Main Results:
- Optimized conditions (pH 5.5, 60 min) yielded Type 1 M protein fragments.
- Type 1 M protein fragments were successfully purified using affinity and gel chromatography.
- Pepsin extraction of Type 3 M protein showed significant pH-dependent SDS-PAGE patterns.
- Affinity chromatography effectively separated Type 3 M protein fragments.
Conclusions:
- Pepsin extraction is a viable method for isolating M protein fragments.
- Purification via affinity chromatography on immobilized fibrinogen is effective for both Type 1 and Type 3 M proteins.
- Type 3 M protein exhibits unique pH-dependent extraction characteristics compared to Type 1.