PathwayStep2684 PathwayStep2683 PathwayStep2682 Monoamines are oxidized to aldehydes by MAOA and MAOB, producing NH3 and H2O2 Authored: Jassal, B, 2008-05-19 12:57:01 Edited: Jassal, B, 2008-05-19 12:57:01 Human monoamine oxidases (MAOs) are flavin-containing enzymes that are present on the outer mitochondrial membrane and act on primary, secondary and tertiary amines. In contrast to the P450s which have a large number of isozymes, MAOs number only two isozymes, MAO-A and MAO-B. These gene products share over 70% sequence identity, are approximately 59KDa in size and have overlapping substrates (for example dopamine, tryamine and tryptamine) but each form also has distinct substrate specificities. MAO-A (primary type in fibroblasts) preferentially oxidises serotonin (5-Hydroxytryptamine) whereas MAO-B (primary type in platelets) prefers phenylethylamine. MAOs are of particular clinical interest because of the use of MAO inhibitors (MAOI) as antidepressants or in the treatment of neurodegenerative diseases. Pubmed11468017 Pubmed9443166 Reactome Database ID Release 43141333 Reactome, http://www.reactome.org ReactomeREACT_416 Reviewed: D'Eustachio, P, 2008-05-28 08:30:54 Oxidative deamination of 5-Hydroxytryptamine by MAOA Dietary tyramine is oxidatively deaminated to an aldehyde by MAOB Oxidative deamination of Phenyethylamine by MAOB