Crystal structures of oxidized and reduced stellacyanin from horseradish roots.

Umecyanin (UMC) is a type 1 copper-containing protein which originates from horseradish roots and belongs to the stellacyanin subclass of the phytocyanins, a ubiquitous family of plant cupredoxins. The crystal structures of Cu(II) and Cu(I) UMC have been determined at 1.9 and 1.