Interaction of N-(2-nitro-4-azidophenyl)-serotonin with two types of monoamine oxidase in rat brain.
The effects of N-(2-nitro-4-azidophenyl) serotonin (NAP-5-HT) on types A and B monoamine oxidase (MAO) in rat brain cortex were studied. In the dark this compound acted as a competitive inhibitor for both types A and B MAO (Ki values of 0.19 microM and 0.21 microM for types A and B MAO, respectively). Upon photolysis, NAP-5-HT became an irreversible inhibitor for only type B MAO. A 50% inhibition was obtained by irradiation of the enzyme in the presence of 35 nM NAP-5-HT. Furthermore the inhibition of type B MAO could be protected by including its substrate phenylethylamine during the irradiation. Under the same photolytic conditions photodependent inhibition of type A MAO by NAP-5-HT was not clearly observed. These results provide further evidence that there is a fundamental difference in the active site of the two types of MAO in brain. NAP-5-HT may be a useful photoaffinity probe for characterizing the active site of type B MAO.
D000345:Affinity Labels; D000818:Animals; D001386:Azides / Q000494:pharmacology*; D001665:Binding Sites; D001667:Binding, Competitive; D002540:Cerebral Cortex / Q000201:enzymology*; D007700:Kinetics; D008297:Male; D008995:Monoamine Oxidase / Q000378:metabolism*; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology*; D010782:Photolysis; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000031:analogs & derivatives* / Q000494:pharmacology
D000345:Affinity Labels; D001386:Azides; D008996:Monoamine Oxidase Inhibitors; C043385:N-(2-nitro-4-azidophenyl)serotonin; D012701:Serotonin; D008995:Monoamine Oxidase