[Purification of the ninth component of human complement (C9)]

Area of Science:

• Biochemistry
• Immunology
• Protein Chemistry

Context:

• The complement system is crucial for innate and adaptive immunity.
• Complement component 9 (C9) is the terminal component of the membrane attack complex (MAC).
• Efficient purification of functional C9 is essential for studying its role in complement-mediated lysis and other biological processes.

Purpose:

• To develop an improved and efficient method for purifying large quantities of human complement component 9 (C9) from plasma.
• To ensure the purified C9 retains its biological activity, specifically hemolytic activity.
• To optimize existing purification techniques, including chromatography, for higher yield and purity.

Summary:

• Human C9 was purified from plasma using a multi-step process involving polyethylene glycol precipitation, plasminogen depletion, DEAE-sephadex A-50 chromatography, and hydroxylapatite (HA) chromatography.
• The purification method was enhanced by modifying column-elution conditions and developing a novel high-flow-rate HA preparation technique.
• The optimized method resulted in a high C9 recovery rate (28.2%) with no detectable impurities via gel electrophoresis or immunochemical analysis, and preserved hemolytic activity.

Impact:

• Provides a reliable and scalable method for obtaining highly pure, functional human C9.
• Facilitates further research into the structure-function relationships of C9 and its role in complement biology.
• Enables the production of C9 for potential therapeutic or diagnostic applications related to complement-mediated diseases.