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Structure of native phosphoglucose isomerase from rabbit: conformational changes associated with catalytic function
Christopher Davies1, Hilary Muirhead
1Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA. davies@musc.edu
Acta Crystallographica. Section D, Biological Crystallography
|February 22, 2003
Summary
Phosphoglucose isomerase (PGI) is a metabolic enzyme and cytokine. Its crystal structure reveals conformational changes in the sugar phosphate-binding site, potentially explaining its catalytic rate-limiting step.
Area of Science:
- Biochemistry
- Structural Biology
- Enzymology
Background:
- Phosphoglucuse isomerase (PGI) is a crucial enzyme in glycolysis and gluconeogenesis.
- PGI also functions as a cytokine, influencing cellular processes like immunoglobulin production and tumor cell differentiation.
Purpose of the Study:
- To determine the crystal structure of native rabbit muscle PGI.
- To identify conformational changes associated with PGI's catalytic function by comparing structures.
Main Methods:
- X-ray crystallography was used to solve the crystal structure of rabbit muscle PGI at 2.5 A resolution.
- Multiple isomorphous replacement and multi-crystal averaging techniques were employed.
- Comparison with existing PGI-inhibitor and PGI-substrate complex structures.
Main Results:
- The crystal structure of native rabbit muscle PGI was successfully determined.
- Conformational changes were observed in the sugar phosphate-binding site, a helix containing His388, and a C-terminal helix.
- These changes correlate with potential catalytic mechanisms and the rate-limiting step of catalysis.
Conclusions:
- The solved crystal structure provides insights into the catalytic mechanism of PGI.
- Observed conformational changes may represent the structural rearrangement limiting the enzyme's catalytic rate.
- This structural data aids in understanding PGI's dual role as an enzyme and cytokine.