Alcohol dehydrogenase activation volume

Ethanol in wine is mainly produced by the alcoholic fermentation of sugar in must. However, grape cells are also capable of forming small quantities, mainly under anaerobic conditions (carbonic maceration see Volume 1, Section 12.9.3). The appearance of traces of ethanol in grapes results from alcohol dehydrogenase activity, which acts as a marker for ripeness. 

The hepatocytes, or parenchymal cells, represent about 80% of the liver by volume and are the major source of metabolic activity. However, this metabolic activity varies depending on the location of the hepatocyte. Thus, zone 1 hepatocytes are more aerobic and therefore are particularly equipped for pathways such as the p-oxidation of fats, and they also have more GSH and GSH peroxidase. These hepatocytes also contain alcohol dehydrogenase and are able to metabolize allyl alcohol to the toxic metabolite acrolein, which causes necrosis in zone 1. Conversely, zone 3 hepatocytes have a higher level of cytochromes P-450 and NADPH cytochrome P-450 reductase, and lipid synthesis is higher in this area. This may explain why zone 3 is most often damaged, and lipid accumulation is a common response (see "Carbon Tetrachloride," for instance, chap. 7). 

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