I am reading the textbook Biology (Campbell et al, 2005), and I am confused.

In Chapter 6.4, on page 104, it says that "In the smooth ER, other enzymes help detoxify drugs <...>", and alcohol is mentioned later.

In Chapter 6.5, on page 111, it says "Peroxisomes in the liver detoxify alcohol <...>"

Googling the question also brought me mixed results.

As I understand it, alcohol detoxification happens in two stages, first oxidising ethanol to the also toxic ethanal, and then oxidising ethanal to acetic acid.

Do these processes happen in different organelles? Is that the reason that both of them are mentioned? Or do they both detoxify alcohol completely, but do it in different circumstances?


1 Answer 1


It seems that there are multiple (oxidative) pathways.

If you look here, there are multiple references showing how ethanol (alcohol) is detoxified.

Alcohol dehydrogenase (ADH) is found in the stomach and starts breaking down ethanol (see first-pass effect, see also the article Gastric alcohol dehydrogenase activity in man: influence of gender, age, alcohol consumption and smoking in a caucasian population). But it is further detoxified elsewhere like the liver cells where the smooth endoplasmic reticulum contains cytochrome P450 2E1 (CYP2E1) and ADH inside the cytosol. The peroxisome also contains catalase which can use peroxide ($H_2O_2$) to oxidize ethanol to acetaldehyde.

This article (Determinants of Alcohol Use and Abuse: Impact of Quantity and Frequency Patterns on Liver Disease) contains a nice figure (2), which shows the pathways which was reproduced here.

Check out this reference also for more details about the pathways.


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