Microsomal Ethanol Oxidizing System
Encyclopedia
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.
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.
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
metabolism that occurs in the microsome in the oxidation of ethanol to acetaldehyde
Acetaldehyde
Acetaldehyde is an organic chemical compound with the formula CH3CHO or MeCHO. It is one of the most important aldehydes, occurring widely in nature and being produced on a large scale industrially. Acetaldehyde occurs naturally in coffee, bread, and ripe fruit, and is produced by plants as part...
. 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
CYP2E1
Cytochrome P450 2E1 , a member of the cytochrome P450 mixed-function oxidase system, is involved in the metabolism of xenobiotics in the body. In humans, the CYP2E1 enzyme is encoded by the CYP2E1 gene...
enzyme, part of the cytochrome P450 family of enzymes, to convert ethanol to acetaldehyde
Acetaldehyde
Acetaldehyde is an organic chemical compound with the formula CH3CHO or MeCHO. It is one of the most important aldehydes, occurring widely in nature and being produced on a large scale industrially. Acetaldehyde occurs naturally in coffee, bread, and ripe fruit, and is produced by plants as part...
. 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
CYP2E1
Cytochrome P450 2E1 , a member of the cytochrome P450 mixed-function oxidase system, is involved in the metabolism of xenobiotics in the body. In humans, the CYP2E1 enzyme is encoded by the CYP2E1 gene...
, seen most conclusively in alcohol dehydrogenase negative deer mice.
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.