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A predicted three-dimensional structure of human cytochrome P450: implications for substrate specificity
M J Zvelebil1, C R Wolf, M J Sternberg
1Biomolecular Modelling Laboratory, Imperial Cancer Research Fund, Lincoln's Inn Fields, London, UK.
Protein Engineering
|February 1, 1991
Summary
This study predicts the human cytochrome P450IA1 structure using P450cam coordinates and sequence alignment. It identifies key residues for function and substrate specificity, aiding future mutagenesis studies.
Area of Science:
- Biochemistry
- Structural Biology
- Computational Biology
Background:
- Human cytochrome P450IA1 is crucial for metabolizing xenobiotics.
- A high-resolution crystal structure for human P450IA1 is currently unavailable.
- Understanding its structure is vital for predicting substrate specificity and drug interactions.
Purpose of the Study:
- To predict a three-dimensional structure for human cytochrome P450IA1.
- To identify residues responsible for substrate specificity and enzyme function.
- To provide a structural model for future experimental validation, such as site-directed mutagenesis.
Main Methods:
- Homology modeling using crystal coordinates of cytochrome P450cam.
- Sequence alignment of human P450IA1 with twelve eukaryotic cytochrome P450 sequences.
- Secondary structure prediction and matching against P450cam.
- Fitting of the substrate 3-methyl-cholanthrene into the predicted active site.
Main Results:
- A 3D model of human cytochrome P450IA1 was successfully built, respecting residue segregation.
- Potential membrane-spanning N-terminal residues (1-26) were identified.
- Specific residues influencing substrate specificity across different P450 gene families were suggested.
- The active site cavity was analyzed for accommodating the substrate 3-methyl-cholanthrene.
- Putative heme-interacting residues were identified.
Conclusions:
- The homology model provides a framework for understanding human P450IA1 structure and function.
- Identified residues are potential targets for site-directed mutagenesis to probe enzyme activity.
- This structural prediction is valuable in the absence of experimental crystallographic data.