Blue copper proteins were among the first proteins to be isolated and their dazzling intense blue color has attracted many scientists. Blue Copper Binding proteins (BCBs) have been purified and characterized in Archea, Bacteria and Eukarya, indicating an important evolutionary role. (Hart et al. 2005). BCBs can be divided into four major groups: cupredoxins, phytocyanins, ephrins, and multicopper oxidases, based on their ability to bind copper and their domain organization. The focus of this research project is on the proteins ceruloplasmin and plantacyanin, which belong to the major groups multicopper oxidases and phytocyanins, respectively. Several studies have shown that ceruloplasmin, which is found in Eukarya is involved in iron metabolism through oxidizing iron. Recently, researchers have found a ?ceruloplasmin-like? protein sequence in the unicellular green alga, Chlamydomonas reinharditii (La Fontaine et al. 2002). In this project, the ceruloplasmin-like protein in Chlamydomonas is purified and characterized to see if it has similar functions as the ceruloplasmin in animals. The second target protein in this project, tomato plantacyanin, shares some similarities with ceruloplasmin. It is the only known single BCB domain blue copper protein that has a noncoordinating residue(Val) at the position of the axial ligand, a feature previously seen only in multicopper oxidases like ceruloplasmin. Plantacyanin is believed to be a key factor in electron transport chains. Here we test this theory by studying its physical properties, e.g. redox potential, after expressing and isolating this tomato protein in E. coli .