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Adenosine kinase from Cryptosporidium parvum
Jon Galazka1, Boris Striepen, Buddy Ullman
1Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, OR 97239-3098, USA.
Molecular and Biochemical Parasitology
|August 2, 2006
Summary
Cryptosporidium parvum relies on adenosine kinase (CpAK) for purine salvage. Characterizing CpAK reveals its potential as a therapeutic target for treating cryptosporidiosis.
Area of Science:
- Parasitology
- Biochemistry
- Drug Discovery
Background:
- Cryptosporidium parvum lacks de novo purine synthesis.
- Adenosine kinase (CpAK) is the sole purine salvage pathway in C. parvum.
- CpAK represents a potential therapeutic target for cryptosporidiosis.
Purpose of the Study:
- To biochemically characterize CpAK.
- To validate CpAK as a drug target.
- To enable drug development against C. parvum.
Main Methods:
- CpAK gene redesign and codon optimization.
- Overexpression of CpAK in Escherichia coli.
- Purification and biochemical characterization of recombinant CpAK.
Main Results:
- CpAK is specific for adenosine and utilizes various phosphate donors (ATP, GTP, UTP, CTP).
- Enzyme kinetics revealed K(m) values of 1.4µM for adenosine and 41µM for ATP.
- Structure-activity data indicated key residue interactions for catalysis.
- 4-nitro-6-benzylthioinosine inhibited CpAK activity.
Conclusions:
- CpAK is essential for C. parvum purine salvage.
- Biochemical characterization provides a foundation for drug development.
- CpAK is a promising drug target for cryptosporidiosis treatment.