Microsomal ethanol oxidising system

Cederbaum, A.I. (1987). Microsomal generation of hydroxyl radicals its role in microsomal ethanol oxidising system (MEOS) activity and requirement for iron. Ann. N. York Acad. Sci. 492, 35-49. 

The enzymes responsible are (1) alcohol dehydrogenase, (2) microsomal ethanol-oxidising system (MEOS), (3) catalase. At low concentrations of ethanol, the dehydrogenase is most important since its is much lower than that of the other two systems. 

The role of short-chain aliphatic alcohols in the regulation of the respirarory burst is controversial, and several mechanisms may be involved in their effects (Seifert and Schultz 1991). Alcohol metabolism has at least four pathways, the most important one being the oxidation of ethanol by alcohol dehydrogenase. After chronic consumption of ethanol or in the presence of high concentration of ethanol, minor pathways such as the microsomal ethanol oxidising system... 

Figure 29.3 Summary diagram of major impacts of ethanol on metabolic pathways. An influx of ethanol disturbs the balance of carbohydrate and fatty acid metabolism. As a result of the oxidation of ethanol, concentrations of NADH and acetyl CoA are increased. Steps in the tricarboxylic acid cycle (TCA) and the mitochondrial pathway for p-oxidatlon of free fatty acids (FFA) which produce these species are inhibited (blue). At the same time, the excess amounts of NADH and acetyl CoA create conditions in which the fatty add synthesis and acidosis are favoured (red). The abundance of acetyl CoA means alcohol precursor metabolites accumulate. See text for a detailed explanation. Abbreviations ADH, alcohol dehydrogenase MEOS, microsomal endoplasmic oxidising system ALD, aldehyde dehydrogenase TG, triglycerides TCA, tricarboxylic acid cycle FFA, free fatty adds.

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