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Streptokinase is one of the best known thrombolytic agents with widespread clinical use. However, its use is not risk-free due to its immunogenicity, hemorrhagic complications and relatively short half-life in circulation. Specific PEGylation of cysteine residue is a useful technique for reducing most of these complications. The aim of this study was designing and producing a cysteine containing mutant of streptokinase, to be used for specific PEGylation. Glut-amic acid 263, which is a surface amino acid in the structure of streptokinase protein, was selected for replacement with cysteine amino acid by site directed mutagenesis. The Glu263 codon was changed to cysteine codon by SOEing PCR technique. Then, the intact and mutated streptokinase genes were inserted into expression vector pET-26b (+). The co-nstructs were transformed to Escherichia.coli Rosetta (DE3) strain and the proteins were expressed by IPTG induction. The proteins were confirmed by SDS-PAGE and western blot analysis, purified by Ni-NTA agarose affinity chroma-tography under denaturing condition with urea and Sephadex G-25 column was applied to remove urea to refold the pr-oteins. This study indicated that by using aforesaid vector and host, cysteine containing mutant gene is expressed well and it will be appropriate for specific PEGylation.

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With the increase of cancer disease and the side-effects of the current treatments, researchers are attempting to find methods with less side-effect. The fern Adiantum capillus-veneris L. has triterpenoid compounds which have anti-tumor characteristics. This study aims to investigate the fatal effect of the extract of this plant on breast cancer (MCF-7) and normal (MRC-5) cell lines using MTT method. A. capillus-veneris specimens were collected from Marzoon Abad Village and were dried at the temperature of 40° C by the use of Soxhlet and Ethanol % 96. Hydroalcoholic extract was produced from the aerial and underground parts of this plant and 3 fractions, i.e., Hexane, Chloroform and Ethyl acetate, were prepared from the extract. The compounds of the plant extract were identified by GC-Mass. The results demonstrate the presence of polyphenolic compounds, terpenoid, fatty acids, wax, alkaloid, N-oxide and fibers, with strong antioxidant effect. The results of the MTT test proved that this extract had a dose-depending fatal effect on the MCF-7 cells and is capable of eradicating the cancer cells. On the other hand, its effect on cancer cells is more than its effect on normal cells. Also, IC₅₀ in both of cell lines induced by the extracts of aerial and underground parts showed a significant difference. The fatal characteristics of the extract are comparable with the cisplatin anti-cancer drug.
 

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Beta vulgaris belongs to the family Amaranthaceae and was found to have halophytic ancestors. The objective of this study was to investigate the effect of sodium chloride on seed germination, therefore the early stages of seedling growth of Beta vulgaris grown under different salinity levels (0, 100, 150 and 200 mM of NaCl) were studied. The experiment was laid out in a completely randomized design (CRD) with four replications. It was revealed that as concentration of NaCl increases, the rate and percentage of germination, length and fresh weight of radicle & plumule and seedling vigour index decrease. In conclusion, our results indicated that salt stress decreased Beta vulgaris seed germination and early seedling growth while induced changes in the anatomical characteristics such as increased level of cutin synthesis on epidermal leaves cells and altered the thickness of vascular system, epidermis and parenchyma in leaves, roots and petioles.
 

 
 

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It has been found that the second isoform of COX enzyme known as COX-2 plays an important role in inflammation and rheumatoid arthritis and osteoarthritis. Thus, designing COX-2 inhibitors to treat inflammation is among the most important goals of researchers. In this study, the inhibitory effect of 3 new imidazole derivatives on COX-2 was evaluated by in silico approach. Molecular docking was done using Autodock Vina and the best binding mode of inhibitors was used as input of molecular dynamics (MD) simulation. MD was performed using Gromacs software for 120 ns. Then, structural and thermodynamic analyzes (ΔG_binding) and prediction of physicochemical properties were performed. RMSD data showed the compounds reached a good equilibrium and had favorable stability during simulation. Also, the RMSF showed that due to binding of inhibitors, the fluctuations of complexes decreased and the active site residues had the lowest amount. Rg, SASA and DSSP analysis showed that the protein structure did not change significantly. It was also found that Ser530 and Tyr355 residues play a more effective role in hydrogen bond formation. Physicochemical parameters determined the good drug-likeness properties for all compounds. Structural and thermodynamic analyzes (MM-PBSA) and IC₅₀ data indicate the favorable inhibitory effect of compound 5b.