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Multifunctionality of liver alcohol dehydrogenase
Advances in Experimental Medicine and Biology
|January 1, 1980
Summary
Liver alcohol dehydrogenase exhibits multiple functions including dehydrogenation, dismutation, and esterolysis, all catalyzed by its isozymes. These activities depend on Zn2+ and sulfhydryl groups, suggesting overlapping yet distinct active sites.
Area of Science:
- Biochemistry
- Enzymology
Background:
- Liver alcohol dehydrogenase (ADH) is a critical enzyme involved in alcohol metabolism.
- ADH exhibits diverse catalytic activities beyond simple alcohol oxidation.
Purpose of the Study:
- To elucidate the multifunctional catalytic activities of liver alcohol dehydrogenase.
- To investigate the reaction mechanisms and cofactor requirements for these activities.
Main Methods:
- Enzyme kinetics studies were performed to analyze dehydrogenation, dismutation, and esterolysis.
- The effects of substrate concentration, temperature, and chemical modifications were examined.
- The role of Zn2+ and sulfhydryl groups was assessed.
Main Results:
- All isozymes of liver ADH catalyze dehydrogenation, dismutation, and esterolysis.
- Dehydrogenation follows a random mechanism, simplifying to ordered BiBi at low alcohol concentrations.
- Esterolysis proceeds via a Uni Bi mechanism, independent of nicotinamide coenzyme.
- Both Zn2+ and sulfhydryl groups are essential for all activities, with evidence for overlapping but distinct domains.
Conclusions:
- Liver ADH possesses multifunctional catalytic capabilities.
- Distinct reaction mechanisms are employed for dehydrogenation, dismutation, and esterolysis.
- The enzyme's structure necessitates both Zn2+ and sulfhydryl groups for its broad activity spectrum.