Copper [Cu(II)] is an ubiquitous transition and trace element in living organisms. It increases reactive oxygen species (ROS) and free-radical generation that might damage biomolecules like DNA, proteins, and lipids. Furthermore, ability of Cu(II) greatly increases in the presence of oxidants. ROS, like hydroxyl (.OH) and superoxide (.O(2)) radicals, alter both the structure of the DNA double helix and the nitrogen bases, resulting in mutations like the AT-->GC and GC-->AT transitions. Proteins, on the other hand, suffer irreversible oxidations and loss in their biological role. Thus, the aim of this investigation is to characterize, in vitro, the structural effects caused by ROS and Cu(II) on bacteriophage lambda DNA or proteins using either hydrogen peroxide (H(2)O(2)) or ascorbic acid with or without Cu(II). Exposure of DNA to ROS-generating mixtures results in electrophoretic (DNA breaks), spectrophotometric (band broadening, hypochromic, hyperchromic, and bathochromic effects), and calorimetric (denaturation temperature [T(d)], denaturation enthalpy [DeltaH], and heat capacity [C(p)] values) changes. As for proteins, ROS increased their thermal stability. However, the extent of the observed changes in DNA and proteins were distinct, depending on the efficiency of the systems assayed to generate ROS. The resulting effects were most evident when Cu(II) was present. In summary, these results show that the ROS, .O2 and .OH radicals, generated by the Cu(II) systems assayed deeply altered the chemical structure of both DNA and proteins. The physiological relevance of these structural effects should be further investigated.

Cyanobacteria has been used as antioxidant in some toxicological models, as well as fluorescent markers and, but little is known about its role in oxidative stress protection. To analyze the effect of phycocianin (PC) on J774A.1 cell cultures, were exposed to an oxidative media generated by ascorbic acid in the presence of Cu(II), and in a control culture without exposure to ROS. After a period of incubation cell viability was obtained and total protein content was measured by Bradford assay; the electrophoretic pattern was obtained by SDS‐PAGE. Results showed that there are differences in the viability and these correlate to the total protein content found under oxidative stress conditions and different PC concentrations. Electrophoretic patterns suggest that the expression of some proteins depend upon the PC concentration added to the oxidative media; this result is related to the content of total protein. Supported by COFAA and EDD, IPN.