Catalytic taurine dioxygenase

Scheme 2.3 Proposed catalytic cycle for taurine dioxygenase as an example of aKG-dependent enzymes [8, 11, 15], The amino acids are numbered according to the sequence of taurine dioxygenase from E. coli [53],...

The archetype Fe(II)/aKG hydroxylase is taurine/ q KG dioxygenase (TauD), an Escherichia coli enzyme that catalyzes the conversion of taurine (2-aminoethanesulfonic acid) to sulfite and aminoacetaldehyde, as illustrated in Scheme 1. TauD catalyzes the hydroxylation of a C H bond on the carbon adjacent to the sulfonate group of taurine. The product of this reaction then decomposes to yield hydrogen sulfite, which serves as an important source of sulfur for many microorganisms. A catalytic mechanism that has been proposed for these enzymes is provided as Scheme 2. Prior to the activation and hydroxylation of the Ci carbon on taurine, q KG binds to the Fe(II) center as a chelate, displacing two of the coordinated waters. Taurine then binds to the enzyme in the vicinity of the Fe(II) center, displacing the remaining water. 

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