Lentil seedling amine oxidase: interaction with carbonyl reagents

Carbonyl reagents containing a primary amino group were covalently bound by lentil seedling amine oxidase to resolve conflicting data for both the number of functional active sites in the dimeric enzyme. Active site titration of highly purified enzyme samples with all the carbonyl reagents extrapolates to 1 mol of inhibitor/mol of enzyme subunit indicating the presence of a cofactor at each enzyme subunit. This result is at variance with numerous previous reports of only one functional cofactor for enzyme dimer in copper amine oxidase.