Trimethylamine dehydrogenase (TMADH) and histamine dehydrogenase (HD) FMN-binding domain. TMADH is an iron-sulfur flavoprotein that catalyzes the oxidative demethylation of trimethylamine to form dimethylamine and formaldehyde. The protein forms a symetrical dimer with each subunit containing one 4Fe-4S cluster and one FMN cofactor. It contains a unique flavin, in the form of a 6-S-cysteinyl FMN which is bent by ~25 degrees along the N5-N10 axis of the flavin isoalloxazine ring. This modification of the conformation of the flavin is thought to facilitate catalysis.The closely related histamine dehydrogenase catalyzes oxidative deamination of histamine.
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