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Schistosomes express two forms of cathepsin D
J Y Wong1, S A Harrop, S R Day
1Queensland Institute of Medical Research, and Australian Centre for International and Tropical Health and Nutrition, Royal Brisbane Hospital, Herston.
Biochimica Et Biophysica Acta
|April 4, 1997
Summary
Researchers identified a cathepsin D-like aspartic protease in the human blood fluke Schistosoma mansoni. This protease is crucial for schistosome survival, potentially aiding in hemoglobin degradation from host blood cells.
Area of Science:
- Biochemistry
- Parasitology
- Molecular Biology
Background:
- Schistosoma mansoni is a parasitic flatworm causing schistosomiasis.
- Aspartic proteases, like cathepsin D, are vital enzymes in various biological processes.
- Understanding parasite-specific enzymes is key to developing targeted therapies.
Purpose of the Study:
- To identify and characterize a cathepsin D-like aspartic protease in adult Schistosoma mansoni.
- To analyze the deduced amino acid sequence and compare it with related enzymes.
Main Methods:
- cDNA sequencing
- Amino acid sequence analysis
- Homology comparison with mammalian cathepsins D and S. japonicum cathepsin D
Main Results:
- A cDNA encoding a cathepsin D-like aspartic protease was identified in Schistosoma mansoni.
- The enzyme consists of a signal peptide, a pro-enzyme peptide, and a mature enzyme of 377 residues.
- The mature enzyme shows 84% amino acid identity to S. japonicum cathepsin D but possesses a unique 43-residue carboxyl terminal extension.
Conclusions:
- The identified aspartic protease is expressed in adult Schistosoma mansoni.
- This enzyme likely plays a significant role in the parasite's ability to degrade host hemoglobin.
- Structural differences from S. japonicum cathepsin D may indicate distinct functional roles or regulatory mechanisms.