Primary amines as uncouplers of electron transport from hydroxylation in the secondary-amine mono-oxygenase system of Pseudomonas aminovorans

Methylamine, ethylamine and n-propylamine caused an oxidation of NADH in the presence of the partially-purified secondary-amine mono-oxygenase system of Pseudomonas aminovorans. The primary amine did not disappear and no hydroxylation product was formed, so it was concluded that primary amines were non-substrate effectors uncoupling NADH oxidation from hydroxylation. K m and V max values were determined for the three primary amines and compared with the values for the corresponding secondary amine substrates. Methylamine competitively inhibited the oxidation of dimethylamine to formaldehyde. It was not possible to establish whether H 2O 2 was formed since the enzyme preparation contained catalase. Substrates and non-substrate effectors were equally effective in causing conversion of a reduced-oxygenated intermediate form of the enzyme back to the original oxidized form.