Although the structural features of the copper
sites in plastocyanin [l] and azurin [2] have been
reported in biological and spectroscopic studies
and crystal structure analyses, less popular ‘blue
copper proteins’ require further study. Blue copper
centers differ structurally not only in their ligating
groups but also in their coordination geometry
around the copper ion. Here, we describe properties
of plantacyanin, one of the blue copper proteins
from cucumber peel. Though the function of
plantacyanin has not yet been established, it is
likely to take part in electron transfer in a system
containing peroxidase, cytochrome c and ascorbate
oxidase.