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Active site amino acid sequence of human factor D
Summary
Researchers isolated and sequenced human Factor D, revealing its active site serine and homology to other serine proteases. This structural data advances understanding of Factor D
Area of Science:
- Biochemistry
- Proteomics
- Molecular Biology
Background:
- Human Factor D is a crucial component of the complement system.
- Understanding Factor D's structure is key to elucidating its function in immune responses.
Purpose of the Study:
- To isolate and determine the N-terminal amino acid sequence of human Factor D.
- To identify the active site of Factor D and compare its structure to other serine proteases.
Main Methods:
- Factor D purification using multiple chromatography techniques (CM-Sephadex C50, Sephadex G-75, hydroxylapatite).
- Peptide generation via cyanogen bromide digestion.
- Automated Edman degradation for N-terminal sequencing.
Main Results:
- Isolated and fragmented human Factor D into three peptides (CNBr I, II, III).
- Determined the N-terminal sequence of Factor D, identifying the active site serine (Gly-Asp-Ser-Gly-Gly-Pro) at residues 12-17.
- Found partial homology between Factor D and rat group-specific protease.
Conclusions:
- The N-terminal sequence of Factor D reveals structural similarities to other serine proteases.
- Further structural analysis is required to fully define Factor D's relationship with other proteases.