Related Experiment Videos
Crystal structure of cod liver class I alcohol dehydrogenase: substrate pocket and structurally variable segments
S Ramaswamy1, M el Ahmad, O Danielsson
1Department of Molecular Biology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Protein Science : a Publication of the Protein Society
|April 1, 1996
Summary
Cod liver alcohol dehydrogenase shares structural similarities with mammalian enzymes but has distinct substrate pockets and proton relay systems. These differences, particularly in loop structures, impact enzyme function and substrate specificity.
Area of Science:
- Biochemistry
- Structural Biology
- Enzymology
Background:
- Alcohol dehydrogenases (ADHs) are crucial enzymes involved in alcohol metabolism.
- Mammalian class I ADHs share conserved structural features.
- Understanding variations in ADH structure across species can reveal insights into substrate specificity and catalytic mechanisms.
Purpose of the Study:
- To elucidate the structural characteristics of cod liver alcohol dehydrogenase.
- To compare the structural framework and substrate pocket of cod ADH with mammalian counterparts.
- To investigate the differences in the proton relay system and their functional implications.
Main Methods:
- X-ray crystallography was used to determine the three-dimensional structure of cod liver alcohol dehydrogenase.
- Comparative structural analysis was performed against horse and human alcohol dehydrogenases.
- Analysis of catalytic domain rotation and substrate pocket topography was conducted.
Main Results:
- Cod liver ADH shares a similar overall structural framework with mammalian ADHs but exhibits significant differences in its substrate pocket, primarily in three loop regions.
- Despite structural variations, the substrate pocket remains hydrophobic with a similar topography to mammalian class I enzymes.
- The proton relay system in cod ADH differs, lacking the conserved His 51 found in mammalian enzymes, and instead utilizes a tyrosine and water molecule, forming a shorter proton relay pathway.
Conclusions:
- Cod liver ADH represents a distinct structural variant within the alcohol dehydrogenase family.
- The observed differences in substrate pocket loops and proton relay systems suggest adaptations for specific substrate interactions or environmental conditions.
- Structural insights into cod ADH contribute to a broader understanding of enzyme evolution and catalytic diversity.