THE CHEMICAL REACTIONS ALLOWING OXI

THE CHEMICAL REACTIONS ALLOWING OXIDATION OF ETHANOL TO ACETALDEHYDE


The oxidation of ethanol produces acetaldehyde (see Figure). The production of acetaldehyde by catalase is limited by the availability of hydrogen peroxide, a potentially harmful byproduct of ethanol metabolism by cytochrome P450. Hydrogen peroxide also can come from a number of other sources, including the enzyme monoamine oxidase, ascorbic acid (vitamin C), and other cytochrome P450 oxidations (Sandri et al. 1990; Simonson et al. 1993; Sinet et al. 1980).
Figure Pathways of ethanol metabolism in the brain. The oxidation of ethanol produces acetaldehyde. The production of acetaldehyde by the enzyme catalase (found in internal cell components called peroxisomes) requires hydrogen peroxide (H2O2). The enzyme cytochrome P4502E1 is present in brain cell structures in the smooth endoplasmic reticulum (microsomes). Alcohol dehydrogenase (ADH) is an enzyme found in the cell’s fluid or cytosol. The enzyme aldehyde dehydrogenase (ALDH), found in the cell’s mitochondria and cytosol, converts acetaldehyde to acetate.
All studies of the oxidation of ethanol to acetaldehyde depend on the ability to measure the accumulation of acetaldehyde. This can occur only if the rate of removal of acetaldehyde is slower than its rate of formation in the system under study. Substantial amounts of acetaldehyde are oxidized to acetate in these in vitro systems. This results in an underestimation of the rate of ethanol metabolism in the brain, because acetaldehyde is metabolized to acetate nearly as quickly as it is formed. Thus, only the net amount of acetaldehyde in the system is accounted for when only acetaldehyde accumulation is measured. Studies of the oxidation of ethanol to acetaldehyde in the brain therefore need to consider these limitations.

ผลลัพธ์ (แอฟริกา) 1:

Die chemiese van etanol na asetaldehied oksidasiereaksies sodat die oksidasie van etanol produseer asetaldehied (sien figuur). Die produksie van asetaldehied deur katalase word beperk deur die beskikbaarheid van waterstofperoksied, 'n potensieel skadelike byproduk van etanol metabolisme deur sitochroom P450. Waterstofperoksied kan ook kom uit 'n aantal ander bronne, insluitend die ensiem monoamienoksidase, askorbiensuur (vitamien C), en ander P450 oksidasies (Sandri et al 1990;. Simonson et al 1993;. Sinet et al 1980).. figuur Pathways van etanol metabolisme in die brein. Die oksidasie van etanol produseer asetaldehied. Die produksie van asetaldehied deur die ensiem katalase (gevind in interne selkomponente genoem peroksisome) vereis waterstofperoksied (H2O2). Die ensiem sitochroom P4502E1 teenwoordig is in die brein sel strukture in die gladde endoplasmiese retikulum (mikrosome). Alkoholdehidrogenase (ADH) is 'n ensiem wat in vloeistof of sitosol die sel se. Ensiem aldehied dehidrogenase die (ALDH), gevind in die sitosol en mitochondria se Cell, Skakel asetaldehied om asetaat. Al die oksidasie van etanol na asetaldehied Studies van afhang van die vermoë om die opeenhoping van asetaldehied meet. Dit kan slegs plaasvind indien die koers van die verwydering van asetaldehied is stadiger as die tempo van die vorming in die stelsel onder studie. Aansienlike bedrae van asetaldehied word geoksideer om asetaat in hierdie in vitro stelsels. Dit lei tot 'n onderskatting van die tempo van etanol metabolisme in die brein, want asetaldehied gemetaboliseer om naastenby so vinnig soos dit gevorm asetaat. So, is slegs die netto bedrag van asetaldehied in die stelsel verantwoordelik vir wanneer daar slegs asetaldehied opeenhoping gemeet. Studies van die oksidasie van etanol na asetaldehied in die brein moet dus hierdie beperkings te oorweeg.