Isolation of human complement factors C3, C5 and H.

Area of Science:

• Biochemistry
• Immunology
• Protein Chemistry

Background:

• Complement factors C3, C5, and H are critical components of the human immune system.
• Efficient and simultaneous purification of these factors is essential for research and potential therapeutic applications.
• Existing purification methods may lack efficiency or the ability to isolate multiple factors concurrently.

Purpose of the Study:

• To develop an improved, simultaneous purification method for complement factors C3, C5, and H from human plasma.
• To achieve high purity and yield of the target complement factors.
• To establish a robust protocol for researchers and clinicians.

Main Methods:

• Utilized QAE-Sephadex batch separation followed by SP-Sephadex chromatography and Sephadex G-200 gel filtration for initial purification.
• Employed DEAE-Sephacel chromatography for simultaneous isolation of factors H and C5 from post-SP-Sephadex material.
• Incorporated anti-C3-Sepharose affinity chromatography to remove residual C3 from the C5 pool.
• Applied maleylation or citraconylation of reduced and alkylated C3 to enable separation of its polypeptide chains via ion exchange chromatography.

Main Results:

• Successfully purified 600 mg of highly pure C3 from 1600 ml of human plasma.
• Simultaneously obtained approximately 70 mg of highly pure factor H and 30 mg of highly pure C5.
• Demonstrated effective removal of C3 contamination from the C5 fraction using specific affinity chromatography.
• Showcased the ability to separate C3 polypeptide chains after chemical modification.

Conclusions:

• The developed method offers an efficient and simultaneous approach for purifying complement factors C3, C5, and H.
• This protocol yields high-purity proteins, suitable for various research and clinical applications.
• The modification of C3 polypeptide chains provides a novel strategy for further fractionation and analysis.