Showing 8 results for Ranaei
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.
Volume 8, Issue 2 (10-2017)
Abstract
Cellulase is one of the industrial enzymes which its production and utilization is increasingly taking into consideration due to global heed to second-generation bioethanol production. Cellulase produced by different organisms such as fungi, bacteria, insects, and plants. With increase in utilization of this enzyme and need for reduction in the enzymes price for production of second-generation bioethanol, the production of recombinant enzyme has been considered noticeably.
In this study, by investigation of corn steep liquor as nitrogen source and second carbon source after glycerol, a new medium is designed based on SYN6 salt medium then biomass and endoglucanase II production by methylotrophic yeast was optimized. Experiments designed by one-factor and response surface methodology used for optimization.
Results showed that optimum conditions for biomass and endoglucanase production are 5.5% (w/v) and 6.15% (w/v) of corn steep liquor respectively. New optimized conditions increased 41.4% and 69.7% for biomass and recombinant enzyme production respectively.
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 9, Issue 3 (Summer 2018)
Abstract
Aims: Glaucoma is an optic neuropathy that causes loss of retinal ganglion cells (RGC) and leads to blindness. This disease is a leading cause of blindness worldwide. For pre-clinical studies and finding novel therapies, using functional animal models is unavoidable. One of these models is the mice treated with N-Methyl-D-Aspartate (NMDA). The aim of this study was the acute induction of ganglion cell death and generation of mouse experimental model of glaucoma by N-Methyl-D-Aspartate.
Materials and Methods: In this experimental study, the creation of model mice with NMDA neurotoxin were created. For this purpose, retinal cell damage was induced in vivo in mice by intravitreal injection of NMDA. After removing the eyes, tissue analyses were performed on sample and control eyes. After tissue staining, the number of ganglion cells and the thickness of the retina layers and Ganglion Cell Complex (GCC) were evaluated. In addition, number of ganglion cells, thicknesses of the retina, and GCC of the optic nerve disc were measured in samples.
One-way ANOVA and SPSS 22 software were used to analyze the data.
Findings: Only 3 days after the injection to eye samples of NMDA, the thickness of the GCC and retinal layers as well as the number of ganglion cells significantly decreased compared to the control samples. The 50% reduction in the number of ganglion cells in the glucoma sample was confirmed.
Conclusion: Three days after the injection of NMDA to eye samples, the thickness of the GCC and retinal layers as well as the number of ganglion cells is significantly decreased compared to the control samples.
Volume 9, Issue 3 (Summer 2018)
Abstract
Aims: Invertase is an enzyme that is widely used in industries. The main source of industrial production of invertase is yeast Saccharomyces cerevisiae (S. cerevisiae). Increasing thermal stability makes an important contribution to improving productivity in related production. The aim of this study was increasing thermal stability of Saccharomyces cerevisiae recombinant protein invertase by site-directed mutagenesis.
Materials and Methods: In the present experimental study, using invertase enzyme from thermophilic bacteria, Thermotoga maritima as template, it was decided to replace the threonine 345 and asparagine 349 amino acid with alanine, using site-directed mutagenesis and in Pichia pastoris, cloning was performed with the SOEing polymerase chain reaction. The activity of natural and mutant recombinant invertase enzymes at different temperatures, different pHs, stability duration, and thermal-performance stability, and Michaelis–Menten kinetics were drawn.
Findings: The thermal-structural stability of the natural and mutant invertease enzymes at 55°C showed that the mutant enzyme had a higher thermal stability at 55°C compared with the natural enzyme. Both natural and mutant enzymes exhibited a similar trend in functional stability. Reduction of Km and increase of Vmax in sucrose substrate and 5-fold increase in Kcat/Km ratio of mutant enzyme was observed.
Conclusion: Site-directed mutagenesis has no negative effect on the amount of production as well as the secretion of recombinant protein invertase and increases enzyme activity. The mutant enzyme has a higher structural stability than the natural enzyme without altering its functional stability.
Volume 11, Issue 20 (Supplementary Issue (Tome 55)- 2007)
Abstract
Today's organizations face a complex set of needs of their stakeholders. They cannot satisfy those needs in a good manner because of economical rationality or inability to prepare suitable equipments. So inter-organizational relationships have been choosen as a strategy which nowadays attract much attention. In fact, each organization has a set of interorganizational relationships voluntarily or involuntarily with other organizations which many organizational advantages and disadvantages have roots in such a inter-organizational relationships. Therefore, the Present research aimed at developing a simulation based model to study inter-organizational relationships. In this model, inter-organizational relationships are documented with process approach, and then. analyzed based on volume, time, human recourses, mutual dependency network and decision. According to the analysis results, "to-be" process is redesigned. These changes are suitability analyzed with simulation and implemented if they are confirmed. Finally this model has been implemented in Agriculture Industry Bureau of Jihad -Agriculture Ministry.
Mohammad Mohsen Moshksar, Mohammad Amin Ranaei, Ahmad Afsari, Seyed Yousef Ahmadi,
Volume 14, Issue 15 (Third Special Issue 2015)
Abstract
In this study, commercially pure copper samples were severely deformed by equal channel angular pressing (ECAP) up to 8 passes in room temperature. The effect of sever plastic deformation on the microstructure, mechanical properties, electrical conductivity and electrical wear resistance of the cupper were investigated. In addition, the effect of induced strain on mechanical properties of the extruded cupper in each pass was studied. Field emission scanning electron microscope micrographs show the extreme evaluation of the microstructure after 4 to 8 ECAP passes, in which a large amount of nano and ultra-fine grains are observable. The mechanical properties of the pure cupper in each pass were estimated by compression testing and Brinell hardness method at room temperature. Yield strength and hardness increased by ∼390 MPa and 75HB respectively after 5-pass ECAP due to finer boundary spacing. Increasing the strength of pure copper led to only a minor decrease of the electrical conductivity. Hence, by applying ECAP, one can obtain the ultra-fine pure copper that can improve the mechanical properties without impairing the electrical conductivity. By reducing the applied strain in each pass (25%) of the ECAP process can be obtain the pure copper with higher strength. The electrical wear behavior of the samples was investigated by electrical discharge machining (EDM). The results indicate that, electrical wear of the extruded samples reduces compare to the original samples.
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.
