Stoichiometry of the Topa Quinone Biogenesis Reaction in Copper Amine Oxidases
- 17 February 1999
- journal article
- research article
- Published by American Chemical Society (ACS) in Biochemistry
- Vol. 38 (10) , 2892-2898
- https://doi.org/10.1021/bi9824994
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.Keywords
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