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Insights into acylphosphatase structure and catalytic mechanism
M Stefani1, N Taddei, G Ramponi
1Department of Biochemical Sciences, University of Florence, Italy. stefani@cesit1.unifi.it
Cellular and Molecular Life Sciences : CMLS
|February 1, 1997
Summary
Acylphosphatase, a small enzyme, has two conserved isoenzymes in vertebrates. Research suggests a substrate-assisted mechanism for its catalytic function, rather than solely enzyme-driven catalysis.
Area of Science:
- Biochemistry
- Enzymology
- Structural Biology
Background:
- Acylphosphatase is a small enzyme (~98 amino acids) found in vertebrates.
- Two highly conserved isoenzymes exist, sharing over 55% sequence homology.
- The precise physiological roles of acylphosphatase isoenzymes remain uncertain.
Purpose of the Study:
- To investigate the catalytic mechanism of acylphosphatase.
- To identify key residues involved in enzyme catalysis.
- To explore potential substrate-assisted catalytic pathways.
Main Methods:
- Protein structure determination (solution and crystal structures).
- Site-directed mutagenesis to probe catalytic residues.
- Analysis of structural data and mutagenesis results.
Main Results:
- Acylphosphatase exhibits a compact structure similar to other phosphate-binding proteins.
- Specific residues crucial for catalysis were identified.
- The identified residues alone may not account for the complete catalytic cycle.
Conclusions:
- A substrate-assisted catalytic mechanism is proposed for acylphosphatase.
- The phosphate group of the substrate may act as a nucleophile.
- This mechanism involves activating catalytic water for enzymatic activity.