Modeling of quinoprotein functions

A b s t r a c t : The model compound of TTQ (tryptophan tryptophylquinone), the active site cofactor of bacterial methylamine dehydrogenases, was synthesized for the first time. 1H NMR analysis and theoretical calculations on the model compound (1) indicate that its molecular geometry is close to that of TTQ in the enzyme active site. The redox potential and spectral characteristics (W-vis and resonance Raman) of 1 were also very similar to those of the native enzymes. Model compound 1 catalyzes the oxidation of benzylamine in CH30H, indicating that it possesses the same chemical functions as methylamine dehydrogenases. Product analysis on the reactions of 1 with several amines indicate that the amine oxidation proceeds via a transamination mechanism. In order t o study structure-reactivity relationships of TTQ, 4-substituted-6,7-indolequinones were also synthesized and their physicochemical properties and catalytic activity in the amine oxidation were compared to those of model compound 1.