Amicyanin is a type I copper protein that plays an integral role in electron transfer.
In bacteria such as Paracoccus denitrificans, amicyanin is part of a three-member redox complex, along with methylamine dehydrogenase (MADH) and cytochrome c-551i.
In the electron transfer mechanism from MADH to heme, amicyanin acts as an electron-accepting intermediate.
It has been shown that inactivation of amicyanin by gene replacement in vivo results in complete loss of ability to grow on methylamine.
Arnout P. Kalverda, Jesus Salgado, Christopher Dennison, and Gerard W. Canters, Biochemistry 1996, 35, 3085-3092.