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Characterization of the CNBr peptides generated from the factor B cleavage fragments, Ba and Bb, by molecular
Insights
Researchers isolated and characterized the Ba and Bb fragments of human factor B from the alternative complement pathway. This study details the specific CNBr peptides composing these crucial complement system components.
Area of Science:
- Biochemistry
- Immunology
- Complement System
Background:
- Human factor B is a key protein in the alternative complement pathway.
- Understanding the structure of factor B's cleavage fragments (Ba and Bb) is essential for elucidating complement system function.
Purpose of the Study:
- To isolate and characterize the specific cleavage fragments, Ba and Bb, derived from human factor B.
- To identify the composition of these fragments in terms of CNBr peptides.
Main Methods:
- Human factor B was treated with factor D and cobra venom factor to generate Ba and Bb fragments.
- Fragments were isolated using preparative polyacrylamide gradient gel electrophoresis.
- Further purification and characterization involved CNBr treatment, high-performance liquid chromatography, and SDS-PAGE.
Main Results:
- The Ba fragment was identified as a single 28,000 CNBr peptide.
- The Bb fragment yielded multiple CNBr peptides: 34,700 (under reducing conditions), 14,500, and 8,300.
Conclusions:
- The study successfully delineated the CNBr peptide composition of human factor B's Ba and Bb fragments.
- These findings provide detailed molecular insights into the structure of key components of the alternative complement pathway.
Abstract:
Highly purified human factor B of the alternative complement pathway was treated with factor D in the presence of cobra venom factor to generate its Ba and Bb cleavage fragments. These cleavage fragments were isolated by preparative polyacrylamide gradient gel electrophoresis followed by electrodialysis elution and treatment with CNBr. The resultant CNBr cleavage peptides were isolated by molecular exclusion high performance liquid chromatography and characterized by SDS polyacrylamide gel electrophoresis. Results of these experiments indicate that the Ba fragment essentially consisted of a 28,000 CNBr peptide, whereas 34,700 (28,000 + 3,500 when characterized under reducing polyacrylamide gel electrophoresis conditions); 14,500 (=20,000); and 8,300 CNBr peptides were derived from the Bb fragment.