Amicyanin is a type I blue copper protein that plays an essential role in electron transfer
In Paracoccus denitrificans bacteria, amicyanin acts as an intermediary of a three-member redox complex along with methylamine dehydrogenase (MADH) and cytochrome c-551i. The electron is transferred from the active site of MADH via the amicyanin copper ion to the cytochrome heme iron. The electron transfer from MADH to cytochrome c-551i does not involve a ternary complex but occurs via a ping-pong mechanism in which amicyanin uses the same interface for the reactions with MADH and cytochrome c-551i.
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