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Showing 3 results for Ranaei Siadat
Ehsan Dehnavi, Seyed Omid Ranaei Siadat, Amir Sahebi, ,
Volume 5, Issue 2 (8-2014)
Abstract
β- Xylosidase from Selenomonas ruminantium (SXA) is one of the most important enzyme for the hydrolysis of cell wall hemicellulose. SXA has potential utility in industrial processes especially production of bioethanol from bagasse. However, this xylosidase lose activity drastically above 50 °C. Each monomer of this homotetramer has four free buried cysteine. It seems that cysteine 286 has no role in protein function. In this study, to investigate effects of free buried cysteine on protein thermal stability, Cys 286 was replaced with the same size amino acid, valine. The mutant and native protein have expressed in Pichia pastoris. Kinetic and thermostability parameters of mutant were compared with the wild type enzyme. While pH optimum, temperature profile and catalytic efficiency of recombinant mutant were be found similar to native enzyme, mutant showed about 65% increase in thermostability respect to the wild type at 55 ˚C. Our results showed that free thiol group of cysteine caused the destabilization. Moreover, hydrophobic side chain of valine could involve in a hydrophobic interaction to stabilize SXA. Elimination of a free cysteine enhanced thermal stability without changing the catalytic efficiency of the enzyme that could be very important for biotechnological applications.
H. Rashedi , S. Arjmand , H. Rashedi, S.o. Ranaei Siadat, M. Pouryaqubi,
Volume 9, Issue 3 (Summer 2018)
Abstract
Aims: Hepatitis B is a viral infection, which can cause serious liver problems. Hepatitis B surface antigen (HBsAg), which is produced as recombinant, is used to produce the Hepatitis B vaccine. The aim of this study was to detect DNA aptamer with high affinity against HBsAg by Systematic Evolution of Ligands by Exponential Enrichment (SELEX).
Materials and Methods: In the present experimental study, SELEX method was used to isolate and sequence a DNA aptamer with high affinity against HBsAg. The affinity of this monoclonal nucleotide sequence was calculated by fluorimetric method. The difference of initial absorption and residual value as a measure for the number of associated sequences were calculated with Prism 5 software by nonlinear regression method, Binding-saturation and one site-total model were performed, and the amount of electron affinity (Kd) was determined.
Findings: After performing the SELEX procedure and evaluating the amplified sequence with agarose gel, the result was positive control sample containing a bond in the range of 72nucleotides, indicating successful amplification of the selected sequence, using selective primers. During cloning steps from existing colonies of PCR reaction with aptamer specific primers, the presence of aptamer was confirmed in Escherichia coli bacteria. The reported aptamer had a stable secondary structure with a free energy of ΔG of less than -6.9kJ and Tm higher than 45°C.
Conclusion: The selected DNA aptamer has a high affinity to the target protein (HbsAg) and can be considered as an alternative for mAbs in chromatography column.
Volume 20, Issue 4 (10-2018)
Abstract
Spirulina platensis is an edible microalga with high protein content (60-70%). Presently, there is a rising interest to evaluate in vitro cytotoxic effect of edible protein after hydrolysis by the gastric protease. Unfortunately, despite widespread researches about the health effect of hydrolyzed proteins in dairy products, very few studies are available in the field of marine microalgae protein. Therefore, this research was aimed to investigate anticancer and antibacterial effects of the dominant protein of S. platensis after hydrolyzed by Trypsin and Chymotrypsin enzymes on Human colon adenocarcinoma cell and Escherichia coli, and Staphylococcus aureus, respectively. The results revealed that ̴ 20-22 kDa protein and its derived peptides decrease bacterial growth and <3kDa peptide fraction was able to significantly reduced SW480 cell viability. Based on this study, we can conclude that Spirulina plantesis is a potential protein source in the future industrial production of functional peptides.
