Identification by gas chromatography-mass spectrometry of an adduct between pure pig plasma benzylamine oxidase and the inhibitor 3,5-diethoxy-4-aminomethylpyridine.

3,5-Diethoxy-4-aminomethylpyridine (B24) interacts with pure pig plasma benzylamine oxidase (BAO), giving a Schiff base with the carbonyl active site. This Schiff base was reduced, isolated by chemical hydrolysis of the enzyme, purified by HPLC and identified by gas chromatography-mass spectrometry (GC-MS) after derivatization. The isolated B24 adduct had the same absorption spectrum, retention time on HPLC and GC and the same mass spectrum as B24-pyridoxamine. B24, which is a reversible enzyme inhibitor, is also a weak substrate and competes with benzylamine, which is the best substrate, for the active site. These results further indicate the presence of pyridoxal-phosphate covalently linked to the pig plasma benzylamine oxidase and involved in the active site of this enzyme.