A great variety of soluble proteins with content of different metals (mainly iron and copper) made the cellular metabolism of these organisms adapt to the synthesis of alternative proteins depending on the relative availabilities of the metal. At cultivation in laboratory conditions Spirulina has a linear form, the protein expression of 21.9 kDa and 20.3 kDa (specific for spiral filaments) is focused on building kDa proteins of 52.0 kDa and respectively 31.8, what is observed in the case of Spirulina cultivation in the presence of copper compounds (Figure 1). The polypeptide with apparent molecular weight of 60.4 kDa identified at cultivation in the presence of copper compounds, is possibly the phytochelatin homodimer of the synthase, which belongs to the class of enzymes that participate in the synthesis of phytochelatins, a class of peptides post-translationally synthesized which play an important role in the tolerance of plants, fungi, algae and cyanobacteria compared to the heavy metals by binding them and diminishing the concentration of free ions. At cultivation in the presence of the coordination compounds of Cu(II), in the protein spectrum of Spirulina appear new polypeptides, with molecular mass of 33.12 kDa. This polypeptide is similar according to the molecular mass with the protein center of reaction of photosystem II that reacts as antibodies. It was determined the polypeptide with the mass of 28.51 kDa which according to the literature data may correspond to the peptides that possess antiviral and antioxidant action as superoxide dismutase. We notice as well polypeptides with molecular masses of 24.5 kDa, 22.2 kDa, 20.0 kDa and 19.1 kDa corresponding to the α- and β- phycocyanin and allophycocyanin subunits. As a result of the comparative study of the polypeptide spectrum from the summary protein fraction extracted from Spirulina biomass cultivated with and without coordination compounds of Cu (II) we can deduce the following conclusion: the electrophoretic spectrum of the summary proteins reflected the emergence of polypeptides with new molecular masses of 33.12 kDa – essential components of the photosystem II acting as antibodies, 28.51 kDa – peptides that possess antiviral and antioxidant action and 60.4 kDa –the phytochelatin homodimer of the synthase. Therefore, the copper coordination compounds affect the photosynthesis processes and the oxidative stress developed by Cu (II) is anihilated by the enzymatic antioxidant system.