Microsomal ethanol oxidizing system

For other uses, see Meos (disambiguation).

The Microsomal Ethanol Oxidizing System (MEOS) is an alternate pathway of ethanol metabolism that occurs in the microsome in the oxidation of ethanol to acetaldehyde. While playing only a minor role in ethanol metabolism in average individuals, MEOS activity increases after chronic alcohol consumption. The MEOS pathway requires the CYP2E1 enzyme, part of the cytochrome P450 family of enzymes, to convert ethanol to acetaldehyde. Ethanol’s affinity for CYP2E1 is lower than its affinity for alcohol dehydrogenase, thus its delayed activity in non-chronic alcohol consumption states. Increase in MEOS activity is correlated with an increase in production of CYP2E1, seen most conclusively in alcohol dehydrogenase negative deer mice.^[1]

The MEOS pathway requires oxidation of NADPH to NADP+, which consumes ATP and dissipates heat, thus leading to the hypothesis that long term drinkers see an increase in resting energy expenditure.^[2]

References

1. ^ Chales S. Lieber. 2004. The Discovery of the Microsomal Ethanol Oxidizing System and Its Physiologic and Pathologic Role. Drug Metabolism Reviews 36:511-529.
2. ^ Francisco Santolaria and Emilio González- Reimers. 2003. Alcohol and Nutrition: an Integrated Perspective in Nutrition and Alcohol: Linking Nutrient Interactions and Dietary Intake. p. 5 Ronald Ross Watson and Victor R. Preedy (eds). Taylor and Francis, CRC Press.