Showing 13 results for Siadat
Volume 4, Issue 3 (2014 2014)
Abstract
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: 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 12, Issue 2 (1-2022)
Abstract
Klebsiella pneumoniae is a gram-negative bacillus of the Enterobacteriaceae family. Despite being part of the natural human microflora, this is an opportunistic pathogen and a major cause of nosocomial infections. The increased emergence of multidrug resistance in Klebsiella pneumoniae has limited the treatment options for this bacterium. Carbon nanotubes (CNT), by improving the stability and solubulity of drugs, could increase the effectiveness of drugs for treatment. The aim of this study is to investigate the antibacterial effect of nanofluid containing functionalized multi-walled carbon nanotubes (f-CNT-NF) on Klebsiella pneumoniae isolated from clinical specimens. For the strain confirmation, biochemical ,API20E kit, and additional differential tests were performed, and antibiotic susceptibility test was performed by the disk diffusion method. The studied strain showed a resistance to all antibiotics such as cefepime.The minimum inhibitory concentration (MIC) was determined using the antibiotic micro dilution method. The MIC was determined in five effect modes including antibiotic (Ab), nanofluid containing functionalized multi-walled carbon nanotubes (f-CNT-NF) , nanofluid containing multi-walled carbon nanotubes (CNT-NF) ,Ab in combination with f-CNT-NF and Ab with CNT-NF. Nevertheless the individual effects of 10 µg mL-1 cefepime or 80 µg of nanofluid with f-CNT-NF did not inhibit the growth of the bacteria, but the co-administration of 10 µg mL-1 cefepime with 80 µg of the f-CNT-NF could inhibit the bacteria`s growth. It was concluded that f-CNT-NF could be more effective in drug delivery at lower concentrations than the free state, which could be used as a tool for optimal drug delivery.
Volume 12, Issue 3 (9-2009)
Abstract
Objectives: Staphylococcus aureus is an important cause of serious infection in both hospital and the community. Methicillin-resistant S. aureus (MRSA) is associated with high morbidity and mortality rates with rapid development of resistance. There is a need for early and reliable detection of MRSA infection to direct antibiotic therapy, and more effectively control cross-infection. In this study, resistance to methicillin was detected by a disk diffusion method, the determination of MIC, and the PCR for mecA gene.
Materials and Methods: A total of 174 S.aureus strains were isolated from different clinical specimens from three teaching Hospitals. Antibiotic susceptibility was determined by disk diffusion method, MIC for oxacillin was made by the agar dilution, and mecA gene was identified by specific primers.
Results: The prevalence of MRSA by three methods ranged from 47% to 50%, and mecA positive isolates were more resistant to all of the antibiotic tested than mecA negative isolates. All S. aureus isolates were resistant to penicillin, and susceptible to vancomycin. The results of agar dilution test indicated a low-level resistance to methicillin (MIC>64mg/l). The distribution of MRSA isolates were uniform between three hospitals, and there were not significant differences in the presence of MRSA between isolates from different clinical specimens.
Conclusion: The PCR method was the best test for routine detection of MRSA in the present study. An additional benefit of the mecA PCR is the potential to generate a susceptibility report, 24h earlier than the time of generation of results of conventional susceptibility testing methods.
Volume 12, Issue 4 (fall 2021)
Abstract
Objective: Premature ovarian failure (POF) is one of the most important reproductive diseases in women under 40 years of age, which affects the quality of life and longevity of these people by causing short-term and long-term complications.
The incidence of POF is a chronic process that takes several years to develop. The patient went through stages such as premature ovarian insufficiency (POI) and decreased ovarian reserve (DOR), in the early stages of the disease decreased ovarian function efficiency (POI) and then with further progression of the disease, the patient decreased ovarian reserve and further reduce their performance. As the disease progresses, the person eventually develops premature and complete ovarian failure, or POF studies have shown that many factors, including surgical trauma, autoimmune diseases, certain drugs, vaccines, and genetic factors, play a role. Genetic studies have shown that several genes are involved in the development of this disease. Part of the regulation of the expression of these genes is the responsibility of small genetic factors called miRNAs.
Materials and Methods: In the present study, bioinformatics information of miRNAs involved in this disease was investigated. For this purpose, genetic databases such as UCSC, NCBI, KEGG, MIRBASE, TARGET SCAN, STRING, etc. were used to access the genes involved in this disease, structural and functional communication, messaging pathways and regulatory miRNA.
Results and Conclusion: The results of this study indicate that three factors, miRNA-187, miRNA-33b and miRNA-33a, are very effective in the development and progression of this disease.
Volume 12, Issue 4 (fall 2021)
Abstract
The biopharmaceutical industry in Iran is developing in parallel with the global trend. Given the risks and costs of research, development, production, and sales of these drugs, firms have moved toward open innovation models across different value chains in the last decade. However, the limited use of technological cooperation methods by the Iranian firms will trap the industry in genericization soon. Accordingly, the development of an open innovation system in the value chain of the Iranian biopharmaceutical industry provides the possibility of continuous development of the industry. In the present study, first, the technological capabilities of the firms in the Iranian biopharmaceutical industry were evaluated, and then some cases of technological cooperation in the industry were studied deeply. Accordingly, considering the "strategic" level of technological capability of firms and also the lessons learned from the multicase study of the experiences of the Iranian pharmaceutical firms, strategies including the completion of the value chain links, the use of export development tools, the supporting of the commercialization in universities and research institutes, the facilitation of technology integration and acquisition and finally the development of smart public financial support to develop are proposed for the development of open innovation system in the Iranian biopharmaceutical industry.
Volume 14, Issue 2 (6-2011)
Abstract
Objective: IL18 is a cytokine that plays an important role in the T-cell-helper type 1 (Th1) response and hence, plasmid-encoded IL18 is considered as a potent genetic adjuvant for DNA vaccine studies. In this study, a bicistronic eukaryotic plasmid capable of secreting a more stable mouse IL18 (fused with Fcγ2a fragment) was constructed and expression of this chimer cytokine was also assessed.
Materials and Methods: RNA purified from stimulated mouse spleenocytes and then cDNA corresponding to mouse IL18 (mIL18) and Fcγ2a fragments were constructed by RT-PCR. Sequential subcloning of mIL18 and IgG2aFc fragments first into pSL1180 and then pSecTag2 plasmids resulted in the fusion of mIL18/Fc and addition of immunoglobulin kappa signal sequence (Igk/mIL18/Fc), respectively. Final cloning of Igk/mIL18/Fc sequence downstream of CMV promoter into the NheI/XmaI sites of pIRES2-GFP plasmid and led to the construction of pIRES-Igk/mIL18/Fc plasmid, which was transfected to HEK293T cell line by Turbofec Transfection reagent and expression analysis, was evaluated by ELISA assay.
Results: Restriction enzyme analysis of pSL-mIL18، pSL-mIL18/Fc، pSec-mIL18/Fc and pIRES- Igk/mIL18/Fc plasmids with the enzymes that were applied for clonings led to the isolation of fragments with expected size and then plasmid of pIRES- Igk/mIL18/Fc was also confirmed following sequencing reactions. Moreover, expression and secretion of mIL18 to the medium was evidenced in transfected 293T cells, compared to non-transfected controls.
Conclusion: pIRES- Igk/mIL18/Fc plasmid possesses the capacity of the cloning and expression of putative antigen gene under the direction of IRES sequence, and also expression of mIL18 as a great secretive genetic adjuvant. This results can be useful to design an efficient DNA vaccine especially for inducing host cellular immune response, moreover, cab be considered a promising for accessing to new generation of DNA vaccine.
Volume 16, Issue 2 (6-2016)
Abstract
Scour around pier in the flow is an Inevitable issue. Estimation of scour depth and understanding the flow field around pier would help us to design with safer factor. The most important factor of scour around pier is changing of streamelines that leads to a system so called local scour. It consist of two vortices: horseshoe vortices and wake vortex. The obstacle creates downflow jet in front of pier that collide with bed sediments and carry them to the downstream, making the horseshoe vortice. The wake vortex is caused by splitting the streamelines and formation of low pressure flow field region and absorption of flow in rear of pier and pick up the bsd sdiments in this district. In this study we used the numerical model SSIIM as a CFD model to simulate flow and scour pattern Simultaneously around a group piers. This model can be used in hydraulic and environment engineering and has the ability of sediment transport calculation in bed transient movement with temporal dependent as the most important advantage in compare with the other CFD models. The verification of this model was implemented by data and results reported for side by side piers examinations as one ofe the group categorize. In this model we considered the k-ε and k-ω seperately as a turbulence model to solve the eddy viscousity of 3D Navier-Stokes flow equations and use their outputs as inputs of sediment transition equations, we used Power-Law scheme as one of the descritization method of First-Order upstreame scheme to solve the flow and sediment equations on the grids. The pressure term of Navier-Stokes equations in cells was calculated by SIMPLE algorithm which is the First-Order upstreame scheme too. Also by changing the G⁄D distant ratio on the other simulation runs, we generated the diagrams with comparative situation with experimental diagrams. Results in the last time of simulation showed there is much more value of horizontal and vertical velocity between the piers than the other sides. It was 57% of final maximum scour depth in first hour of calculation. Similarly to velocity, The final scour patterns showed there is more scour depth counters between the piers. In details it was deriven that the scour depth pattern was symmetric in early time of calculation, but with time passing it appeared more in the region of between the piers. Although Numerical results show the SSIIM model have calculated the erosion depth in front of piers with high accuracy resulted from good calculation of downflow, comparisons between model results and data show the scour depth pattern that the model calculated the wake vortices behind the piers and Interference the horseshoe vortex between the piers with overestimate value and there are deeper countors of scour depth than experiment diagram. Also the RMS index of scour depth has been calculated in the grid and it represented the values of 0.0353 for k-ε model and 0.0899 for k-ω model. Therefore, the k-ε turbulence model resulted better scour depth pattern calculated in compare with k-ω turbulece model.
Seyedeh Sara Siadati, Neda Ahmadi Kamazani,
Volume 19, Issue 132 ( February 2023)
Abstract
The aim of this study was to evaluate the physicochemical characteristics (extraction yield, color development, fatty acid profile, iodine value, saponification value, phytosterol profile(, DPPH radical scavenging activity and oxidative stability of cold pressed hazelnut oil extracted from microwave pretreated kernels (0, 2.5, 5 and 7.5 min, 600 W). The results showed that microwave pretreatment of persian hazelnut kernel increased the oil extraction yield, color development and phytosterol contents of all oil samples. Also, no significant differences (p≥ 0.05) were observed during microwave pretreatment in saponification value (188-191 mg KOH/g oil) and fatty acids profile of hazelnut kernel oil samples. The predominant unsaturated fatty acids in oil samples in all treatments were determined as oleic acid C18:1c (77.43-78.32%) and linoleic acid C18:2c (9.85-10.18%), respectively. The predominant phytosterols in oil samples in all treatments were determined as β-sitosterol, Δ-5-Avenasterol, Campesterol, Δ-7-stigmastanol and sitostanol. The highest DPPH radical scavenging activity were observed in oil samples of MW-0 (90.62%) and MW-2.5 (89.94%), respectively. In addition, peroxide value, anisidine value and totox value of control hazelnut oil (MW-0) and pretreated hazelnut oil (MW-2.5) at an oven temperature of 160 ° C at 0, 3, 6 and 9 h intervals were determined. Also oxidative stability index (OSI) was determined by rancimat test at 120 ° C. The results indicated that microwave pretreatment is a promising strategy for amplification of oil extraction yield and phytosterol contents in obtained oil from persian hazelnut kernels.
Keywords: microwave roasting, cold press, oxidative stability, hazelnut kernel oil, phytosterols
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.