Isolation of the terminal complement complex from target sheep erythrocyte membranes

Area of Science:

• Immunology
• Molecular Biology
• Biochemistry

Background:

• The terminal complement pathway is a critical component of the innate immune system.
• Understanding the structure of the terminal complement complex (TCC) is essential for elucidating its function in cell lysis and immune regulation.

Purpose of the Study:

• To isolate and characterize the terminal complement complex (TCC) from sheep erythrocyte membranes.
• To determine the subunit composition and molecular weight of the TCC.

Main Methods:

• Solubilization of erythrocyte membranes with Triton X-100.
• Isoelectric focusing and immunoelectrophoresis for initial TCC localization.
• Sepharose 6B chromatography for purification.
• Dodecyl sulfate gel electrophoresis (SDS-PAGE) for subunit analysis.

Main Results:

• The TCC was successfully isolated and focused at pH 5.8-6.5.
• Chromatography yielded a complex with a molecular weight of 800,000-4,000,000 Da.
• SDS-PAGE revealed seven protein bands, with estimated molar ratios suggesting a complex stoichiometry.
• Two-dimensional SDS-PAGE indicated disulfide bonds in certain subunits, likely C5b and C8alpha.

Conclusions:

• The study successfully isolated and characterized the terminal complement complex from sheep erythrocyte membranes.
• The molecular weight and subunit composition of the TCC were elucidated, providing insights into its structure.
• The findings contribute to a deeper understanding of complement-mediated immune responses.