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Updated: Jul 12, 2026
05:51
Direct Detection of the Acetate-forming Activity of the Enzyme Acetate Kinase
Published on: December 19, 2011
Structural analyses of a malate dehydrogenase with a variable active site.
J K Bell1, H P Yennawar, S K Wright
1Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis 55455, USA.
The Journal of Biological Chemistry
|June 5, 2001
Summary
Malate dehydrogenase
Area of Science:
- Biochemistry
- Enzymology
- Structural Biology
Background:
- Malate dehydrogenase catalyzes malate oxidation to oxaloacetate.
- Enzyme specificity is conferred by active site arginines coordinating substrate carboxyl groups.
Purpose of the Study:
- Investigate the role of Arg-153 in malate dehydrogenase substrate specificity using the R153C mutant.
- Determine the structural basis for altered enzyme activity in the R153C mutant.
Main Methods:
- X-ray crystallography of the NAD binary complex.
- Analysis of NAD-pyruvate ternary complex.
- Energy-minimized molecular modeling of R153C analogues.
Main Results:
- The R153C mutation shifts a bound sulfate ion in the active site, suggesting substrate misalignment.
- Pyruvate binds via backbone interactions, not arginine coordination, in the R153C mutant.
- Molecular models indicate potential favorable interactions for modified side chains, but native activity is not restored.
Conclusions:
- Precise positioning of the Arg-153 guanidino side chain is critical for optimal substrate orientation and high enzymatic activity.
- The R153C mutation leads to reduced catalytic turnover due to altered substrate binding and positioning.
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