Subunit Structure of Nonheme Iron-Containing Dioxygenases
Dioxygenases are enzymes that catalyze the incorporation of two atoms of molecular oxygen into various substrates. These enzymes have been discovered in all types of living organisms and shown to perform a variety of functions. Among these, cleavage of the aromatic ring is one function that appears to depend largely, perhaps entirely, upon this type of enzyme. Cofactors involved in these enzymes are nonheme iron, heme or copper (1). The indole ring-cleaving enzyme, tryptophan 2,3-dioxygenase, is known to contain heme as a cofactor (2). A flavonol-cleaving enzyme, quercetinase, has been reported to be a copper protein (3). With the exception of these two enzymes, most of the other dioxygenases, if not all, contain nonheme iron as the cofactor. Among these, some enzymes contain the ferrous form of iron and some, the ferric form.
KeywordsSodium Dodecyl Sulfate Ferric Iron Native Enzyme Subunit Structure Nonheme Iron
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