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The ALDH2 gene is about 44 kbp in length and contains at least 13 exons which encode 517 amino acid residues. Except for the signal NH2-terminal peptide, which is absent in the mature enzyme, the amino acid sequence deduced from the exons coincided with the reported primary structure of human liver ALDH2.
Aldehyde dehydrogenase is a polymorphic enzyme [3] responsible for the oxidation of aldehydes to carboxylic acids. [3] There are three different classes of these enzymes in mammals: class 1 (low K m, cytosolic), class 2 (low K m, mitochondrial), and class 3 (high K m, such as those expressed in tumors, stomach, and cornea).
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]
One such reaction is: AH 2 + O 2 ↔ A + H 2 O 2. Sometimes an oxidase reaction will look like this: 4A + 4H + + O 2 ↔ 4A + + 2H 2 O. In this case, the enzyme is taking electrons from the substrate, and using free protons to reduce the oxygen, leaving the substrate with a positive charge. The product is water, instead of hydrogen peroxide as ...
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.
The values below are standard apparent reduction potentials (E°') for electro-biochemical half-reactions measured at 25 °C, 1 atmosphere and a pH of 7 in aqueous solution. [1] [2] The actual physiological potential depends on the ratio of the reduced (Red) and oxidized (Ox) forms according to the Nernst equation and the thermal voltage.
The reaction from ethanol to carbon dioxide and water proceeds in at least 11 steps in humans. C 2 H 6 O (ethanol) is converted to C 2 H 4 O (acetaldehyde), then to C 2 H 4 O 2 (acetic acid), then to acetyl-CoA. Once acetyl-CoA is formed, it is free to enter directly into the citric acid cycle (TCA) and is converted to 2 CO 2 molecules in 8 ...
Exon shuffling was first introduced in 1978 when Walter Gilbert discovered that the existence of introns could play a major role in the evolution of proteins. [3] It was noted that recombination within introns could help assort exons independently and that repetitive segments in the middle of introns could create hotspots for recombination to shuffle the exonic sequences.