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Engineering yeast alcohol dehydrogenase. Replacing Trp54 by Leu broadens substrate specificity
1Department of Chemistry, ETH, Zurich, Switzerland.
Protein Engineering
|May 1, 1995
Summary
Researchers modified yeast alcohol dehydrogenase (Adh) by changing a key residue, Trp54 to Leu. This engineered enzyme now efficiently oxidizes longer, branched-chain alcohols, expanding its catalytic capabilities.
Area of Science:
- Biochemistry
- Enzyme Engineering
- Structural Biology
Background:
- Alcohol dehydrogenase (Adh) is crucial for alcohol metabolism.
- The crystal structure of horse liver Adh provides insights into enzyme mechanisms.
- Yeast Adh's substrate specificity is influenced by specific amino acid residues.
Purpose of the Study:
- To investigate the role of Tryptophan 54 (Trp54) in yeast alcohol dehydrogenase.
- To engineer yeast Adh for improved catalysis of branched-chain alcohols.
- To understand how amino acid substitutions affect enzyme activity and substrate specificity.
Main Methods:
- Analysis of horse liver alcohol dehydrogenase crystal structure.
- Site-directed mutagenesis to alter Trp54 to Leucine (Leu) in yeast Adh.
- Enzyme activity assays with various alcohol substrates.
Main Results:
- The Trp54 residue in yeast Adh was identified as a steric hindrance for branched alcohols.
- Mutating Trp54 to Leu created a variant yeast Adh enzyme.
- The engineered Leu-54 yeast Adh efficiently catalyzed the oxidation of longer straight-chain and branched-chain alcohols.
Conclusions:
- The Trp54 residue dictates substrate specificity in yeast alcohol dehydrogenase.
- Enzyme engineering by site-directed mutagenesis can enhance catalytic efficiency for specific substrates.
- The Leu-54 variant broadens the substrate scope of yeast Adh for industrial applications.