The copper amine oxidases are ubiquitous quinoproteins which catalyze the oxidative deamination of a primary amine to the corresponding aldehyde,with subsequent reduction of dioxygen to hydrogen peroxide.These enzymes contain two cofactors,an organic cofactor topaquinone (TPQ) together with a cupric ion.Whereas the role of TPQ is well understood,there is still debate in the literature as to whether the oxidative half-reaction can proceed at all in the absence of active-site metal.Recent biochemical studies are fairly consistent with a passive role of copper in the catalyzed amine oxidation process.Recently,we have evidenced that electrogenerated 3,4-iminoquinone species l_(ox) (Scheme 1) acts as a potent catalyst for the autorecycling oxidation of benzylamine (3200% turnover yield),following the same pyridoxal-like transamination mechanism than that reported for TPQ cofactor.
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