Ethanol metabolic pathways

Alderman, J, Takagi, T, and Lieber, C. S. (1987), Ethanol-metabolizing pathways in deer-mice, J. Biol. Cfifffl. 262, 7497-7502,... 

Glycolysis Metabolic pathway involving the conversion of glucose to lactic acid or ethanol. 

Microorganisms under anaerobic growth conditions have the ability to utilise glucose by the Embden-Mereyhof-Parnas pathway.4 Carbohydrates are phosphorylated through the metabolic pathway the end products are two moles of ethanol and carbon dioxide.5... 

The conversion of glucose proceeds via its splitting into pyruvic acid and hydrogen, which is bound as NADPH. Pyruvic acid is subsequently decarboxylated to C02 and acetaldehyde (bound to the coenzyme-A), which is subsequently rehydrogenated to ethanol. The overall reaction delivers therefore two molecules of ethanol and two C02 for every glucose unit. Notice that such a simplified metabolic pathway does not display the energy fluxes, e.g., in the form of ATP/ADP interconversion. 

The metabolic pathways of chloroform metabolites are well understood. It appears that both the mode of oral administration and the vehicle affect metabolism. Additional data investigating the mode and vehicle of administration would be useful in order to understand the role of these factors in the mechanism of chloroform s toxicity. The co-administration of other compounds (e.g., ethanol) has been shown to alter chloroform metabolism and toxicity. Further investigations of the hazards associated with exposure to complex mixtures containing chloroform would be useful. 

There are only a limited number of chemical manipulations that a single enzyme can perform, so that for a major chemical change, more than one enzyme is required for example, to convert glucose into ethanol or laetie aeid, more than ten enzymes are required and they function as a coordinated sequence. Such a sequence is called a pathway. Since the first pathways to be elucidated were in the field of metabolism, the term metabolic pathway is a familiar term to almost all biochemists. However, the... 

Oral solution Concomitant use of amprenavir oral solution and ritonavir oral solution is not recommended because the large amount of propylene glycol in amprenavir oral solution and ethanol in ritonavir oral solution may compete for the same metabolic pathway for elimination. 

First-order kinetics Minor metabolic pathway Induced by ethanol Interferes with metabolism of other drugs... 

Oxidation of ethanol. Although the major metabolic pathway for alcohols such as ethanol is oxidation catalyzed by alcohol dehydrogenase (see below), ethanol can also be metabolized by cytochrome P-450. The product, ethanal, is the same as produced by alcohol dehydrogenase. The isoform of cytochrome P-450 is CYP2E1. The mechanism may involve a hydroxylation to an unstable intermediate, which loses water to yield ethanal. Alternatively, a radical mechanism could be responsible. The importance of this route of metabolism for ethanol is that it is inducible (see chap. 5), assuming more importance after repeated exposure to ethanol such as in alcoholics and regular drinkers. 

During the biological aging of sherry, the concentration of ethanol decreases because of its consumption by flor yeast. Its respiration via the tricarboxylic acid pathway (Suarez-Lepez and Inigo-Leal, 2004) provides the main source of carbon and energy. Acetaldehyde is the main organic byproduct of ethanol metabolism, but other volatile compounds, notably acetic acid, butanediol, diacetyl, and acetoin, can also be formed. In addition,... 

The first metabolic pathway that we encounter is glycolysis, an ancient pathway employed by a host of organisms. Glycolysis is the sequence of reactions that metabolizes one molecule of glucose to two molecules ofpyruvate with the concomitant net production of two molecules of ATP. This process is anaerobic (i.e., it does not require O2) inasmuch as it evolved before the accumulation of substantial amounts of oxygen in the atmosphere. Pyruvate can be further processed anaerobically (fermented) to lactate (lactic acidfermentation) or ethanol (alcoholic fermentation). Under aerobic conditions, pyruvate can be completely oxidized to CO2, generating much more ATP, as will be discussed in Chapters 17 and 18. 

The second pathway for ethanol metabolism is called the ethanolinducible microsomal ethanol-oxidizing system (MEOS). This cytochrome P450-dependent pathway (Section 26.4.2) generates acetaldehyde and subsequently acetate... 

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