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Ligand binding and structural perturbations in cytochrome c peroxidase. A crystallographic study
1Center for Advanced Research in Biotechnology, University of Maryland, Rockville 20850.
The Journal of Biological Chemistry
|February 15, 1990
Summary
Crystal structures reveal how cytochrome c peroxidase interacts with ligands like cyanide and nitric oxide. Ligand binding causes distinct structural changes in the enzyme's active site, particularly affecting Arg-48 and proximal residues.
Area of Science:
- Biochemistry
- Structural Biology
- Enzymology
Background:
- Cytochrome c peroxidase (CCP) is a key enzyme in cellular redox processes.
- Understanding ligand interactions is crucial for elucidating enzyme mechanisms.
Purpose of the Study:
- To determine the high-resolution crystal structures of CCP complexes with cyanide, nitric oxide, carbon monoxide, and fluoride.
- To investigate the structural consequences of ligand binding on the enzyme's active site and proximal region.
Main Methods:
- X-ray crystallography to determine and refine crystal structures.
- Analysis of atomic coordinates to identify structural changes.
Main Results:
- Significant structural rearrangements in the distal heme pocket, including movement of Arg-48 and His-52, and altered water molecule arrangements.
- Ligand-specific interactions of Arg-48: moving away from cyanide, nitric oxide, and carbon monoxide, but towards fluoride.
- Unique proximal side perturbations upon nitric oxide binding, involving Trp-191 and His-175, indicating increased residue mobility.
Conclusions:
- Ligand binding induces distinct conformational changes in cytochrome c peroxidase.
- Nitric oxide binding elicits unique proximal side structural changes not solely dependent on iron's spin or oxidation state.