Alcohol Dehydrogenase, or aldehyde reductase, is found in a wide variety of species (even those which don’t consume alcohol!) because the primary purpose of a dehydrogenase enzyme is to utilize a mechanism to convert alcohol into aldehydes or ketones. ADH can not only oxidize ethanol to acetaldehyde (as most college students can relate to) but they can also oxidize secondary, cyclic secondary, or hemi-acetal alcohols.
Each of the subunits on ADH has two different domains; an NAD binding domain which is shown in purple and green, and also an alcohol (substrate) binding domain which is shown in blue and yellow. These two subunits with their respective domains makes ADH active as a dimer in humans.
Another note about structure is that ADH uses two molecules to act as tools and help it perform a reaction on ethanol when ingested. A zinc atom is used to hold and position the alcohol group on ethanol. The other tool utilized is a large NAD cofactor which is the work-horse and actually performs the reaction. The mechanism to describe how this works can be found here:
Works Cited:
Alcohol Dehydrogenase. 20 May, 1999. Retrieved from http://www.users.csbsju.edu/~hjakubow/classes/rasmolchime/99ch331proj/alcoholdehydro/index.htm. Feb 27, 2011.
Goodsell, D. (2001, December). Alcohol Dehydrogenase. Retrieved from http://www.rcsb.org/pdb/101/motm.do?momID=13
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