 Monoamine oxidase A and B share roughly 70% of their structure and both have substrate binding sites that are predominantly hydrophobic.Two tyrosine residues (398, 435, 407 and 444) in the binding pocket that are commonly involved in inhibitor activity have been hypothesized to be relevant to orienting substrates, and mutations of these residues are relevant to mental health.Four main models have been proposed for the mechanism of electron transfer (single electron transfer, hydrogen atom transfer, nucleophilic model, and hydride transfer) although there is insufficient evidence to support any of them.