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Cholesterol Efflux Assay
Published on: March 6, 2012
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Structural characterization of human cholesterol 7α-hydroxylase
Wolfram Tempel1, Irina Grabovec2, Farrell MacKenzie1
1Structural Genomics Consortium, University of Toronto, Toronto, Ontario, M5G 1L7, Canada.
Journal of Lipid Research
|June 15, 2014
Summary
The crystal structure of cholesterol 7α-hydroxylase (CYP7A1) reveals how it binds cholesterol for bile acid synthesis. This provides insights into cholesterol metabolism and enzyme function.
Area of Science:
- Biochemistry
- Structural Biology
- Enzymology
Background:
- Hepatic bile acid synthesis is a primary cholesterol elimination pathway in mammals.
- Cholesterol 7α-hydroxylase (CYP7A1) catalyzes the rate-limiting step in bile acid production.
Purpose of the Study:
- To determine the structural basis for CYP7A1's stereospecific hydroxylation of cholesterol.
- To understand the molecular mechanisms of substrate binding and product inhibition.
Main Methods:
- X-ray crystallography of ligand-free CYP7A1 and its complexes.
- Structure-based site-directed mutagenesis (T104L).
Main Results:
- The crystal structure reveals a binding motif positioning cholesterol for C7 hydroxylation.
- Specific residues accommodate the substrate's aliphatic side chain.
- Complex structure with 7-ketocholesterol explains its inhibitory effect.
Conclusions:
- CYP7A1 structural data offer a molecular basis for understanding 7α-hydroxylase diversity.
- Insights into cholesterol-metabolizing enzyme adaptation and function.
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