Inhibition of monoamine oxidase by 7-chloro-4-nitrobenzofurazan.
7-Chloro-4-nitrobenzofurazan (NBD-Cl) is a potent inhibitor of both types of monoamine oxidase (MAO). NBD-Cl competitively inhibited the oxidative deamination of kynuramine catalyzed by human placenta MAO-A, the oxidative deamination of benzylamine catalyzed by bovine liver MAO-B, the oxidative deamination of serotonin catalyzed by rat brain MAO-A, and the oxidative deamination of phenylethylamine catalyzed by rat brain MAO-B. In addition, a time-dependent inactivation of MAOs by NBD-Cl has been demonstrated upon incubation of the enzyme preparations with NBD-Cl at pH 9, but not at pH 7.5. The time-dependent inhibition of MAO by NBD-Cl could be prevented by the addition of 4-nitrophenyl azide, an active site-directed label of MAO, during incubation of the enzyme with NBD-Cl. On the basis of these findings, it is suggested that at pH 9, NBD-Cl modifies one (or more) essential lysine residue(s) in the active sites of the two types of MAO.
Fu
R C
RC
Division of Immunology, Beckman Research Institute of the City of Hope, Duarte, California 91010.
Liu
X F
XF
Chen
S U
SU
D000818:Animals; D001572:Benzofurans / Q000494:pharmacology*; D001667:Binding, Competitive; D001921:Brain / Q000201:enzymology; D002417:Cattle; D005260:Female; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008928:Mitochondria / Q000201:enzymology; D008930:Mitochondria, Liver / Q000201:enzymology; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology*; D010920:Placenta / Q000201:enzymology / Q000648:ultrastructure; D011247:Pregnancy; D051381:Rats
D001572:Benzofurans; D008996:Monoamine Oxidase Inhibitors; C043708:7-chloro-4-nitrobenzofuran