ALDH2: Difference between revisions

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== Inhibitors and activators ==

''ALDH''2 can be selectively inhibited by Daidzin, as ''ALDH''1 by Antabuse (disulfiram, DS, tetraethylthiuram disulfide), an early alcoholic treatment, as it causes accumulation of acetaldehyde resulting in heavier hangover symptoms. Daidzin is more specific to ''ALDH''2 than to ''ALDH''1, this could be due to a smaller substrate-binding cleft than of ''ALDH''1. The daidzin binding sites are spread over all four subunits. The fully bound daidzin is buried from 90%. The isoflavon ring structure conducts extensive Van der Waals contacts with the surrounding residues, including long contact with Cys302. Cys302 was identified as an important catalyst group. The separation of Daidzin O4′-hydroxyl oxygen from Cys302 sulfur atoms is 3.7 Å, and there is no covalent interaction. Despite the general similarity of the ''ALDH''2 apo and daidzin structures, the conformation has been locally altered. The lateral chain of Cys302 moves 2.5 Å from the site to avoid close contact with the O4′-phenoxy ring of Daidzin. Other isoflavonoid derivatives show some inhibitory impact on ''ALDH''2, although prunetin does not result in structural changes as it binds only one subunit per tetramer. Studies of structural activity indicate that the 7-O position can be replaced by several straight chain alkyls with terminal polar functions such as -OH, -COOH, or -NH<sub>2</sub>. It was observed that longer ethyl group has better hydrophobic interactions resulting in better binding, longer chains can result in lesser affinity due to more complex formation of both polar and nonpolar interactions at the same time<ref>DOI: 10.1021/jm800488j</ref>.

Alda-1 (N-(1,3-benzodioxol-5-ylmethyl)-2,6-dichlorobenzamide) is considered as chemical chaperone for ALDH2. Even though it shares overlapping binding sites with daidzin, binding results in activation of structurally distorted ALDH2. Structural complex of ALDH2 and Alda-1 shows that Alda-1 binds at the entrance to the active site and does not interfere with catalytic residues. As Alda-1 block part of substrate site it is suggested dependence on substrate size. Concentration dependence of Alda-1 activation at saturating concentrations of acetaldehyde, propionaldehyde, butyraldehyde, benzaldehyde, phenylacetaldehyde and DACA were observed. Smaller linear aldehydes were activated by Alda-1, activation decreases with increasing length of aldehydes. Presence of Alda-1 with ALDH2*2 shows greater activity increase than with WT, this suggests that Alda-1 promotes structural and functional rescue than only increasing effective concentration within active site. Distortions starting with 246 residues through the catalyst site, especially Glu268, ending with Glu478. The site of coenzyme binding is reliant on the coenzyme binding, the active site remains even less ordered. Alda-1 has no direct contact with residues from the active site, but forms close interactions with Phe459 and Trp177 near Phe465 and Glu268. This hypothesizes that the binding of Alda-1 could reorient abnormal dynamics in both regions to improve enzyme efficiency<ref>DOI: 10.1038/nsmb.1737</ref>.

After additional screening another most potent activator was identified as Alda-64 (2-(azepane-1-carbonyl)-N-(2chlorobenzyl)-2,3-dihydrobenzo (b) <1,4> dioxine-6-sulfonamide) as Alda-1 it is more specific in favor of ALDH2. Different mutations react differently to each activator. Alda-64 increased activity of ALDH2*3 and ALDH2*5 to WT levels, greater effect than with Alda-1. On the other hand, ALDH2*4 and ALDH2*5 were activated better by Alda-1. This suggests fundamentally different structural changes in each mutation<ref name="nov2020"/>.

== References ==

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 == Inhibitors and activators ==
 ''ALDH''2 can be selectively inhibited by Daidzin, as ''ALDH''1 by Antabuse (disulfiram, DS, tetraethylthiuram disulfide), an early alcoholic treatment, as it causes accumulation of acetaldehyde resulting in heavier hangover symptoms. Daidzin is more specific to ''ALDH''2 than to ''ALDH''1, this could be due to a smaller substrate-binding cleft than of ''ALDH''1. The daidzin binding sites are spread over all four subunits. The fully bound daidzin is buried from 90%. The isoflavon ring structure conducts extensive Van der Waals contacts with the surrounding residues, including long contact with Cys302. Cys302 was identified as an important catalyst group. The separation of Daidzin O4′-hydroxyl oxygen from Cys302 sulfur atoms is 3.7 Å, and there is no covalent interaction. Despite the general similarity of the ''ALDH''2 apo and daidzin structures, the conformation has been locally altered. The lateral chain of Cys302 moves 2.5 Å from the site to avoid close contact with the O4′-phenoxy ring of Daidzin. Other isoflavonoid derivatives show some inhibitory impact on ''ALDH''2, although prunetin does not result in structural changes as it binds only one subunit per tetramer. Studies of structural activity indicate that the 7-O position can be replaced by several straight chain alkyls with terminal polar functions such as -OH, -COOH, or -NH<sub>2</sub>. It was observed that longer ethyl group has better hydrophobic interactions resulting in better binding, longer chains can result in lesser affinity due to more complex formation of both polar and nonpolar interactions at the same time<ref>DOI: 10.1021/jm800488j</ref>.
+Alda-1 (N-(1,3-benzodioxol-5-ylmethyl)-2,6-dichlorobenzamide) is considered as chemical chaperone for ALDH2. Even though it shares overlapping binding sites with daidzin, binding results in activation of structurally distorted ALDH2. Structural complex of ALDH2 and Alda-1 shows that Alda-1 binds at the entrance to the active site and does not interfere with catalytic residues. As Alda-1 block part of substrate site it is suggested dependence on substrate size. Concentration dependence of Alda-1 activation at saturating concentrations of acetaldehyde, propionaldehyde, butyraldehyde, benzaldehyde, phenylacetaldehyde and DACA were observed. Smaller linear aldehydes were activated by Alda-1, activation decreases with increasing length of aldehydes. Presence of Alda-1 with ALDH2*2 shows greater activity increase than with WT, this suggests that Alda-1 promotes structural and functional rescue than only increasing effective concentration within active site. Distortions starting with 246 residues through the catalyst site, especially Glu268, ending with Glu478. The site of coenzyme binding is reliant on the coenzyme binding, the active site remains even less ordered. Alda-1 has no direct contact with residues from the active site, but forms close interactions with Phe459 and Trp177 near Phe465 and Glu268. This hypothesizes that the binding of Alda-1 could reorient abnormal dynamics in both regions to improve enzyme efficiency<ref>DOI: 10.1038/nsmb.1737</ref>.
 After additional screening another most potent activator was identified as Alda-64 (2-(azepane-1-carbonyl)-N-(2chlorobenzyl)-2,3-dihydrobenzo (b) <1,4> dioxine-6-sulfonamide) as Alda-1 it is more specific in favor of ALDH2. Different mutations react differently to each activator. Alda-64 increased activity of ALDH2*3 and ALDH2*5 to WT levels, greater effect than with Alda-1. On the other hand, ALDH2*4 and ALDH2*5 were activated better by Alda-1. This suggests fundamentally different structural changes in each mutation<ref name="nov2020"/>.
 == References ==
 <references/>