Phytocyanins characterization

The first class is cupredoxins—single-domain blue copper proteins composed of only one BCB domain. These proteins include plastocyanin, azurin, pseudoazurin, amicyanin, auracyanins, rusticyanin, halocyanin, and sulfocyanin (see Section IV). Plantacyanin of the phytocyanin family (Section V), subunit II of the cytochrome c oxidase, and the recently characterized nitrosocyanin also fall into this class. The last two are single BCB domain polypeptides closely related structurally to cupredoxins, but harboring, respectively, a binuclear copper site known as CuA and a novel type of copper-binding site called red (see Sections IX and X). 

The third class consists of proteins that are composed of one or more BCB domains fused to a sequence domain(s) characteristic of evolutionarily unrelated protein families. Such a mosaic domain organization has been found in the phytocyanin protein family, stellacyanins, uclacyanins, and the recently characterized dicyanins (Section V) in blood coagulation factor VIII (Section VIII) and in nitrous oxide reductase (Section IX). 

The phytocyanins differ from the other small blue proteins in that the normal methionine ligand of the copper ion is replaced by a glutamate residue [24]. The phytocyanins as well as auracyanin are also characterized by their high extent of glycosylation which, in some cases, doubles the weight of the protein [68,71-73],... 

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