Microbial oxidation of amines. Partial purification of a mixed-function secondary-amine oxidase system from Pseudomonas aminovorans that contains an enzymically active cytochrome-P-420-type haemoprotein

摘要

p1. Crude extracts of iPseudomonas aminovorans/i grown on methylamine, di-methylamine, trimethylamine or trimethylamine iN/i-oxide contain an enzyme or enzyme system catalysing the NADH- or NADPH- and oxygen-dependent oxidation of dimethylamine to methylamine and formaldehyde. 2. The enzyme has been partially purified about five-fold. It is unstable, but can be stabilized by addition of 5% (v/v) ethanol. 3. The partially purified enzyme will utilize either NADH (iK/isubim/i/sub 6.5μm) or NADPH (iK/isubim/i/sub 13.2μm): The following secondary amines have been shown to be substrates: dimethylamine, ethylmethylamine, diethylamine, methyl-in/i-propylamine, ethyl-in/i-propylamine, in/i-butylmethylamine and iN/i-methylethanolamine. The iKsubm/sub/i values and comparative reaction rates for each substrate have been determined. Where the alkyl groups are different, the aldehyde products are derived from both groups. 4. The enzyme system has a pH optimum of 6.8 and is inhibited by mercurials, thiol compounds, cyanide and carbon monoxide. 5. The partially purified preparation had a spectral maximum at 412nm with shoulders at 427 and 550nm. Reduction with dithionite or NAD(P)H bleached the 412nm peak, and the shoulder at 427nm became a peak. Additional peaks appeared at 550 and 580–588nm. Reduction of a preparation bubbled with carbon monoxide enhanced and sharpened the Soret peak and caused it to shift to 422nm. 6. Analysis of the preparation showed the presence of flavin, acid-extractable iron and non-acid-extractable iron in the proportion 1.1:1.9:1. On reduction with dithionite or NADPH the preparation showed an electron-paramagnetic-resonance signal at around ig/i=1.946./p