Copper amine oxidases are important enzymes, which contribute to the regulation of mono- and polyamine levels. Each monomer contains one Cu(II) ion and 2,4,5-trihydroxyphenylalanine (TPQ) as cofactors. They catalyze the oxidative deamination of primary amines to aldehydes with a ping-pong mechanism consisting of a transamination. The mechanism is followed by the transfer of two electrons to molecular oxygen which is reduced to hydrogen peroxide. Inhibitors are important tools in the study of catalytic properties of copper amine oxidases and they also have a wide application in physiological research. In this study, purification of the chickpea seedling amine oxidase, was done via salting out by ammonium sulfate and dialysis, followed by DEAE-cellulose column chromatography. By using the Lineweaver - Burk plot, the Km and Vm of the enzyme were found to be 3.3 mM and 0.95 mmol/min/mg, respectively. In this study, the interaction of chickpea diamino oxidase with tetraethylene- pentamine was studied. Analysis of kinetic data indicated that tetraethylenepentamine (with Ki=0.1 mM) inhibits the enzyme by linear mixed inhibitory effect.

Cyclosporine A (CsA), a cyclic polypeptide metabolite extracted from the fungus, is used clinically to combat organ graft rejection in transplant subjects. Previous studies have shown that CsA exposure enhances the production of reactive oxygen species (ROS) and lipid peroxidation, which are directly involved in CsA toxicity. To protect cells and organs against ROS, the human body has evolved a highly antioxidant protection system to neutralize free radicals. The aim of this study was to investigate the effect of CsA on mRNA expression of anti-oxidant GSTO2. To do this, Jurkat cells were incubated for 24 h with different doses of CsA, ranging from 1-80 µg/ml, and the IC50 of CsA was calculated to be 40 µg/ml. Subsequently, Jurkat cells were treated with 3 µg/ml CsA for 24 h and the gene expression of GSTO2 was quantified by quantitative Real-time PCR. Results showed that the mean (SD) expression of the GSTO2 gene in CsA treated cells was 1.10 (0.07) (when assuming an expression level in untreated cells of 1.0). However, statistical analyses showed that the alterations were not significant (t=2.29, df=2, P=0.149). These findings suggest that at this concentration of CsA, other antioxidant enzymes are up-regulated in Jurkat cell lines to detoxify free radicals induced by CsA.

In addition to biochemical, physiological and morphological analysis, molecular studies provide additional information for establishing phylogenetic relationships among different species and strains of the genus Dunaliella. In the present study, based on neighbor- joining analysis of the nuclear rDNA ITS sequence, a novel strain of the green algae Dunaliella viridis was identified from Maharlu salt lake in Shiraz, Iran. The phylogenetic tree shows that the new strain is part of a clade containing several strains of D. viridis. The new strain was designated Dunaliella viridis MSV-1 and submitted to the GenBank under the accession number HQ864830. The optimum salinity for MSV-1 growth is between 1.0 to 1.5 M NaCl and does not turn red up to 4.5 M NaCl, confirming identity of the isolated strain. With respect to growth response to copper toxicity, increase in Cu2+ concentration from 1 to 30 µM, caused progressive increase in cell number ml-1 of culture over time, whereas reduction in cell number occurred at 100 and 200 µM Cu+2. Nano copper (colloidal copper with 40 nm dimensions) showed less toxicity compared to the ionic form. Cell number ml-1 of culture did not change up to 200 µM nano copper but decreased at 500 µM. In conclusion, the analysis of the ITS sequence is a reliable basis for establishing evolutionary relationships among species and strains of the genus Dunaliella and due to rapid growth at 1.5 M NaCl and high cell density, D. viridis MSV-1 is a good candidate for biofuel production from microalgae.