Amine dehydrogenase possesses an α2β2 structure with each smaller β subunit possessing a TTQ protein cofactor.
Amine dehydrogenase, studied in Paracoccus denitrificans, at least transiently forms a ternary complex to catalyze methylamine-dependent cytochrome c-551i reduction. Within this complex, electrons are transferred from the TTQ cofactor of MADH to the Type 1 copper center of amicyanin, and then to the heme of the cytochrome.
References
Davidson VL (August 2004). "Electron transfer in quinoproteins". Archives of Biochemistry and Biophysics. 428 (1): 32–40. doi:10.1016/j.abb.2004.03.022. PMID15234267.