Pyrogallol, enzyme inhibition

Substrates of COMT include xenobiotics catechols, catecholamines, and catechol estrogens. Three functional classes of chemicals are known to inhibit COMT. S-Adenosyl-I-homocysteine (SAH) is a potent inhibitor of COMT as well as the other SAM-dependent methyltransferases. Inhibition results from SAH binding to the SAM binding site on the enzyme. Certain divalent ions such as Ca+2 and trivalent metal ions such as the salts of lanthanides, neodymium, and europium are excellent inhibitors of COMT. A number of catechol-type substrates such as pyrogallol, fla-vonoids, pyrones, pyridenes, hydroxyquiolines, 3-mercaptotyramine, and tropolones are irreversible inhibitors of COMT. 

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