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Directed molecular evolution of cytochrome c peroxidase
A Iffland1, P Tafelmeyer, C Saudan
1Institut de Chimie Organique and Institut de Chimie Minerale et Analytique, Université de Lausanne, CH-1015 Lausanne, Switzerland.
Biochemistry
|September 9, 2000
Summary
Directed evolution enhanced cytochrome c peroxidase (CCP) activity against guaiacol by 300-fold. Key mutations, including distal arginine to histidine, altered substrate specificity and revealed new roles for active site residues.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Cytochrome c peroxidase (CCP) from Saccharomyces cerevisiae naturally oxidizes cytochrome c.
- Understanding enzyme substrate specificity is crucial for biocatalysis and drug development.
Purpose of the Study:
- To engineer CCP with enhanced activity and altered substrate specificity towards small organic molecules like guaiacol.
- To investigate the role of active site residues, particularly distal arginine (Arg48), in enzyme function.
Main Methods:
- Directed molecular evolution using DNA shuffling and high-throughput screening.
- Isolation and characterization of mutant CCP enzymes.
Main Results:
- Achieved a 300-fold increase in activity against guaiacol and up to 1000-fold increased specificity.
- Identified mutations, notably Arg48 to Histidine, as critical for enhanced phenolic substrate activity.
- Revealed a gatekeeper role for distal arginine in controlling substrate access to the active site.
Conclusions:
- Directed evolution can successfully alter enzyme substrate specificity and enhance catalytic activity.
- The distal arginine in CCP is essential not only for stabilizing intermediates but also for regulating substrate access.
- This study demonstrates the power of directed evolution for solving biochemical challenges beyond rational design.