AI Article Synopsis
- The biogenesis of topa quinone (TPQ) from tyrosine in phenylethylamine oxidase involves a 6-electron oxidation using 2 moles of O2, resulting in the production of H2O2.
- The production rate of H2O2 is measured at 1.0 min-1, which is slightly lower than the TPQ formation rate of 1.5 min-1.
- The established stoichiometry of the reaction (E-Tyr + 2O2 → E-TPQ + H2O2) supports proposed mechanisms for TPQ biogenesis and dismisses several alternative pathways.
Article Abstract
The stoichiometry of the topa quinone biogenesis reaction in phenylethylamine oxidase from Arthrobacter globiformis (AGAO) has been determined. We have shown that the 6e- oxidation of tyrosine to topa quinone (TPQ) consumes 2 mol of O2 and produces 1 mol of H2O2/mol of TPQ formed. The rate of H2O2 production is first-order (kobs = 1.0 +/- 0.2 min-1), a rate only slightly lower than the rate of TPQ formation directly determined previously (kobs = 1.5 +/- 0.2 min-1). This gives the following net reaction stoichiometry for TPQ biogenesis: E-Tyr + 2O2 --> E-TPQ + H2O2. This stoichiometry is in agreement with recently proposed mechanisms for TPQ biogenesis, and rules out several possible alternatives.
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| http://dx.doi.org/10.1021/bi9824994 | DOI Listing |
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