(Alcohol:NAD+ oxidoreductase; EC 18.104.22.168)
Alcohol dehydrogenase (ADH) catalyzes the oxidation of alcohol
and the reduction of aldehydes as shown below:
RCH2OH + NAD+ RCHO + NADH + H+
The enzyme occurs in various mammalian tissues but is found in
relatively high concentrations in liver and kidney. It is a
zinc-containing enzyme and is activated by glutathione and
EDTA and inhibited by heavy metals. ADH from equine liver has
a molecular weight of 80,000, while the yeast enzyme has a
molecular weight of 141,000.
Alcohol dehydrogenase is widely used for the determination of
ethanol in biological fluids. It can also be used in coupled
enzyme reactions for determination of metabolites in
biological fluids. It's optimum pH is 8.6 to 9.0 and it has
an extension coefficient of 12.6 and isoelectric point is 5.4.
The enzyme is activated with sulfhydryl reagents, like
mercapethanol and dithiotreitol.