Help needed: chemistry of alcohol addiction

Pedro Mendes pedro at enzyme.demon.co.uk
Thu Mar 28 17:10:21 EST 1996

Another interesting feature of ethanol metabolism is that the
pathway of ethanol degradation (alcohol dehydrogenase followed
by acetaldehyde dehydrogenase) results in a net production of
reducing equivalents (2 NADH molecules per molecule of EtOH

Large amounts of EtOH increase the NADH/NAD+ ratio. This should
therefore stimulate respiration but as it happens acetaldehyde
inhibits the respiratory chain as well as acetaldehyde 
dehydrogenase, its own converting enzyme. This leaves the liver 
cells with an unmbalanced NADH/NAD+ ratio that potentially affects
many other pathways.

By the way, it is the production of NADH in the degradation of 
EthOH that allows alcoholics to eat very little: they are getting 
most of their energy from this pathway.

Pedro Mendes
home: pedro at enzyme.demon.co.uk , work: prm at aber.ac.uk | Aberystwyth,
http://gepasi.dbs.aber.ac.uk/pedro/prmhome.htm        | Dyfed, Wales,
PGP mail welcome! (public key on demand)              | U.K. (Eur.Un.)

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