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However, this effect is not absolute: during the 1980s, there has been a steady increase in the number of Japanese alcoholics who carry the ALDH2*2 mutation. A strong social pressure to drink have overcome this genetic barrier to alcoholism. [22] Disulfiram, which inhibits ALDH2 and causes a similar effect, has been used as an alcohol-quitting aid.
ALDH2 pictured on the left, is an enzyme which breaks down acetaldehyde. [20] [21] Regions highlighted in yellow are structural and allow ALDH2 to fold properly. [20] [21] The region highlighted in red can vary between individuals (right). [22] Individuals who have a G in their DNA will have normal folding and function of ALDH2. [20]
The reaction is the result of an accumulation of acetaldehyde, a metabolic byproduct of the catabolic metabolism of alcohol, and is caused by an aldehyde dehydrogenase 2 deficiency. [ 4 ] This syndrome has been associated with lower than average rates of alcoholism, possibly due to its association with adverse effects after drinking alcohol. [ 5 ]
Several drugs (e.g., metronidazole) cause a similar reaction known as disulfiram-like reaction. Yokoyama et al. found that decreased enzyme activity of aldehyde dehydrogenase-2, caused by the mutated ALDH2 allele, contributes to a higher chance of esophageal and oropharyngolaryngeal cancers.
ALDH2*1 is a common allele , but about 40% of people of East Asian ethnicity have one or two copies of the dominant ALDH2*2 instead, which causes ALDH2 deficiency. If deficient people drink ethanol, they suffer from alcohol flush reaction due to acetaldehyde accumulation. [3] Four Alda-1 molecules bind to each monomer of ALDH2 tetramer.
Causes of vitamin B12 deficiency. There are a few reasons why someone might develop a vitamin B12 deficiency. Following a vegan diet for years is a big one, says Deborah Cohen, ...
ALDH2, which has a lower K M for acetaldehydes than ALDH1 and acts predominantly in the mitochondrial matrix, is the main enzyme in acetaldehyde metabolism and has three genotypes. A single point mutation (G → A) at exon 12 of the ALDH2 gene causes a replacement of glutamate with lysine at residue 487, resulting in the ALDH2K enzyme. [8]
In 1949, E. Racker defined one unit of alcohol dehydrogenase activity as the amount that causes a change in optical density of 0.001 per minute under the standard conditions of assay. [55] Recently, the international definition of enzymatic unit (E.U.) has been more common: one unit of Alcohol Dehydrogenase will convert 1.0 μmole of ethanol to ...