Search for: enzyme-activity
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    Determination of heavy metal ions by an amperometric biosensor based on glucose oxidase immobilized onto single-walled carbon nanotubes/Nile blue nanocomposite

    , Article Journal of the Iranian Chemical Society ; Volume 15, Issue 8 , 2018 , Pages 1765-1774 ; 1735207X (ISSN) Jahangirzadeh Varjovi, M ; Sabzi, R. E ; Borghei, S. M ; Sharif University of Technology
    Springer Verlag  2018
    An enzymatic electrochemical biosensor was prepared based on glucose oxidase (GOD) immobilized on single-walled carbon nanotubes/Nile blue (Nb–SWCNTs) nanocomposite cross-linked with glutaraldehyde on graphite electrode. The function of glucose biosensor is based on the electrocatalytic reduction of H2O2 generated by the reaction of the enzyme with glucose molecules. The biosensor was characterized by Fourier transform infrared (FTIR) spectroscopy, emission scanning (FESEM), UV–Vis spectrometry, and voltammetric and amperometric methods. Parameters influencing the performance of the biosensor, namely pH and applied potential, were optimized. Inhibition was carried out for the detection of... 

    Study of Enzyme (Chymotrypsin) -Core/Shell (Fe3O4 @ Au) Nanoparticle Bioconjugate

    , M.Sc. Thesis Sharif University of Technology Kamal Ahmadi, Mahmoud (Author) ; Vosoughi, Manoochehr (Supervisor) ; Seyf Kordi, Ali Akbar (Supervisor)
    Conjugation of proteins to nanoparticles has numerous applications in sensing, imaging, delivery, catalysis, therapy and control of protein structure and activity. Therefore, characterizing the nanoparticle–protein interface is of great importance. A variety of covalent and non-covalent linking chemistries have been reported for nanoparticle attachment. Typically, a specific protein residue is linked directly to the nanoparticle core or to the ligand. As conjugation often affects the protein structure and function, techniques to probe structure and activity are assessed Characterization studies of nanoparticle–protein complexes show that the structure and function are influenced by the... 

    Investigation of intestinal enzyme activity and effects of non-starch polysaccharide on it

    , Article International Journal of Engineering and Technology(UAE) ; Volume 7, Issue 4 , 2018 , Pages 28-31 ; 2227524X (ISSN) Piryaei, M ; Motamedi, A ; Mehrabi Far, A ; Sharif University of Technology
    Science Publishing Corporation Inc  2018
    This experiment investigates the effects of utilizing Rahnama cultivar with high non-starchy polysaccharide content and supplementation of xylanase enzyme in poultry feed on the productivity features, nutrient digestibility and intestinal enzymes activity of 21-47 week laying hens. The experiment was conducted quite randomly and in factorial design that included eight treatments with 4 wheat levels (zero, 23, 46 and 69% that contained 1.8, 2.0, 2.2, 2.4% of xylose respectively) and two level enzymes (with and without enzyme) and 5 replications (6 hens) in each replication. During the experiment, by xylose level increase in diet, the weight (p > 0.05) and mass of the egg (p > 0.01) decreased... 

    Investigating on Filtration of Solid Particles in Culture Media after Fermentation

    , M.Sc. Thesis Sharif University of Technology Maleki, Maziar (Author) ; Roosta Azad, Reza (Supervisor)
    In biotechnology processes, in addition of culture media there is a solid phase which dispensed across the system.In most of bioprocesses, first operational unit for downstream treatment is the separation of this particles from fermentation liquor. In contrast with other categories like inorganic chemistry, solid particles in fermentation liquor (which the main part of it is biomass itself) have complicated physical & rheological properties. For example, all of biomass species are hydrophilic and sometimes form colloidal solutions.With this perspective, separation of solid phase from fermentation liquor is a hard challenge in this kind of processes.In this research, with regard of great... 

    Spectrophotometric determination of sulfide based on peroxidase inhibition by detection of purpurogallin formation

    , Article Ecotoxicology and Environmental Safety ; Volume 91 , 2013 , Pages 117-121 ; 01476513 (ISSN) Ghadiri, M ; Kariminia, H. R ; Roosta Azad, R ; Sharif University of Technology
    This paper presents a new method for spectrophotometirc detection of sulfide applying fungal peroxidase immobilized on sodium alginate. The sensing scheme was based on decrease of the absorbance of the orange compound, purpurogallin produced from pyrogallol and H2O2 as substrates, due to the inhibition of peroxidase by sulfide. Absorbance of purpurogallin was detected at 420nm by using a spectrophotometer. The proposed method could successfully detect the sulfide in the concentration range of 0.6-7.0μM with a detection limit of 0.4μM. The kinetic parameters of Michaelis-Menten with and without sulfide were also calculated. Possible inhibition mechanism of peroxidase by sulfide was deduced... 

    Fabrication of Enzyme Biosensor for Heavy Metal Detection

    , M.Sc. Thesis Sharif University of Technology Jahangirzadeh, Mir Ali (Author) ; Borghei, Mehdi (Supervisor) ; Sabzi, Reza (Supervisor)
    In this project identification of heavy metals has been studied by using glucose oxidase enzyme. Measurement of heavy metals such as mercury (II) nitrate, lead (II) nitrate and cadmium nitrate are based on inhibitory of glucose oxidase enzyme. To do this, two modified electrodes has stabilized on a graphite electrode. Nanocomposite of single wall carbon nanotube with Nile Blue is foundation of the first working electrode. Biological component of the electrode is glucose oxidase enzyme that bovine serum albumin and glutaraldehyde are helping enzyme in immobilization and these materials cause enzyme to cross link with the foundation. This biosensor has great stability and suitable linear... 

    Processing Fermented Lipase

    , M.Sc. Thesis Sharif University of Technology Asadollahi Chaghoosh, Aida (Author) ; Roosta Azad, Reza (Supervisor) ; Yeganeh Sarkandi, Shahin (Supervisor)
    Lipases (triacylglycerol acylhydrolases) are industrial enzymes that have wide applications in the detergent, pharmaceutical and food industries. Pseudomonas aeruginosa strain is known to be suitable for lipase production due to its stability in organic solvents, resistance to temperature and pH. Lipases are usually secreted extracellularly, and its isolation from the culture medium is very important. The most cost-effective separation method is filtration which is more economical than centrifuge. Here, the use of filtration method is important from two aspects of creating clearance and maintaining enzyme activity. The equipment in this research is the filter press, whose initial tests are... 

    The characterization of proteins involved in toxic metal resistance of a bacterial strain isolated from mine site using a proteomic approach

    , Article Pollution Research ; Volume 28, Issue 3 , 2009 , Pages 337-343 ; 02578050 (ISSN) Nemati, F ; Arabian, D ; Roostaazad, R ; Gade, W. N ; Shitole, M. G ; Sharif University of Technology
    We investigated the response of a bacterial strain isolated from low grade complex zinc and lead sulfide mines to metals toxicity (i.e., zinc, manganese, nickel, cobalt, copper, arsenate, chromium, lead, and mercury). The bacterium was identified as a strain of Aciditiobacillus ferrooxidans. The isolate showed good resistance to most of the toxic metals. The proteomics approach was used to identify the differentially expressed proteins under heavy metal stress in this strain. Four of the differentially expressed proteins were identified as major outer membrane protein of A. ferrooxidans, ribulose bisphosphate carboxylase large subunit of A. ferrooxidans, putative DNA restriction methylase,... 

    Optimization of l-asparaginase immobilization onto calcium alginate beads

    , Article Chemical Engineering Communications ; Volume 204, Issue 2 , 2017 , Pages 216-220 ; 00986445 (ISSN) Bahraman, F ; Alemzadeh, I ; Sharif University of Technology
    Taylor and Francis Ltd  2017
    In this study, anti-leukemic enzyme L-asparaginase (E.C. from Escherichia coli ATCC 11303 was modified by the microencapsulation technique onto calcium alginate beads. Using response surface methodology (RSM), a three-level full factorial design, the values of concentration of sodium alginate, concentration of calcium chloride, and enzyme loading were investigated to obtain the highest residual L-asparaginase (L-ASNase) activity % (immobilized enzyme activity/free enzyme activity). The effects of the studied factors on immobilization were evaluated The predicted values by the model were close to the experimental values, indicating suitability of the model. The results presented that... 

    Cis-trans proline isomers in the catalytic domain of calcineurin

    , Article FEBS Journal ; Volume 286, Issue 6 , 2019 , Pages 1230-1239 ; 1742464X (ISSN) Teixeira, J. M. C ; Guasch, A ; Biçer, A ; Aranguren Ibáñez, Á ; Chashmniam, S ; Paniagua, J. C ; Pérez Riba, M ; Fita, I ; Pons, M ; Sharif University of Technology
    Blackwell Publishing Ltd  2019
    Calcineurin is an essential calcium-activated serine/threonine phosphatase. The six NMR-observable methionine methyl groups in the catalytic domain of human calcineurin Aα (CNA) were assigned and used as reporters of the presence of potential cis-trans isomers in solution. Proline 84 is found in the cis conformation in most calcineurin X-ray structures, and proline 309, which is part of a highly conserved motif in phosphoprotein phosphatases, was modeled with a cis peptide bond in one of the two molecules present in the asymmetric unit of CNA. We mutated each of the two prolines to alanine to force the trans conformation. Solution NMR shows that the P84A CNA mutant exists in two forms,... 

    Comparing the Performance of Centrifuge, Membrane Filter and Filter Press for Clarification of Lipase Enzyme

    , M.Sc. Thesis Sharif University of Technology Taher Aslani, Ahmad Reza (Author) ; Rousta Azad, Reza (Supervisor)
    Lipases (Triacyl Glycerol Acyl Hydrolase, EC. are multidimensional biocatalysts which have many applications in food industrials, dairy, fats and oils processing, detergents, synthesis of pure chemical and pharmaceutical materials, paper industrial and cosmetics. Generally, industrial enzymes are produced extracellularly, so their separation from a low-cost complex medium (usually used for production) is one of the cost stages in their production process. Filtration is the most economical method of separation in the production of enzymes, but due to the small size of colloidal particles and cell masses present in the fermentation environment, its use is subject to limitations. In... 

    Experimental Study of Biological Synthesis, Stabilization and Delivery of the Recombinant Protein of Chondroitinase

    , Ph.D. Dissertation Sharif University of Technology Askaripour, Hossein (Author) ; Vossoughi, Manouchehr (Supervisor) ; Alemzadeh, Iran (Supervisor) ; Khajeh, Khosro (Supervisor)
    In this research, immobilization method was employed to increase the thermal stability of Chondroitinase ABC I (cABC I) enzyme. In first step, magnetite nanoparticle (Fe3O4) was selected as a support and cABC I enzyme was attached via the adsorption method. The results showed that pH=6.5, temperature 15 ˚C, enzyme-to-support mass ratio 0.75, and incubation time 4.5 hr were the appropriate conditions for immobilizing cABC I enzyme on Fe3O4 nanoparticle. It was also found that the optimum pH for free and immobilized enzymes was 7.6 and 8.0, respectively. The maximum activity of free enzyme was obtained at 25 ˚C, whereas the activity of immobilized enzyme was almost constant in the temperature... 

    Alkaline protease production by immobilized cells using B. licheniformis

    , Article Scientia Iranica ; Volume 20, Issue 3 , 2013 , Pages 607-610 ; 10263098 (ISSN) Maghsoodi, V ; Kazemi, A ; Nahid, P ; Yaghmaei, S ; Sabzevari, M. A ; Sharif University of Technology
    In recent years there has been potential increase in the use of alkaline protease as industrial catalysts. Many major industrial and commercial applications, such as food and textile industries, and medical diagnoses, are highly dependent on the protease enzyme. In the cell immobilization technique, the free movement of microorganisms is restricted in the process, and a continuous system of fermentation can be used. In the present work, this technique has been used for alkaline protease production using different carriers, such as chitosan, corn cob and corn tassel. Enzyme activity before immobilization (72 h) was 78.3 U/ml. Corn cob, with 65% immobilization capacity and the highest enzyme... 

    Studies on glutaraldehyde crosslinked chitosan hydrogel properties for drug delivery systems

    , Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 62, Issue 11 , 2013 , Pages 605-611 ; 00914037 (ISSN) Mirzaei, B. E ; Ramazani, S. A. A ; Shafiee, M ; Danaei, M ; Sharif University of Technology
    Chitosan was crosslinked with different amount of glutaraldehyde to prepare appropriate hydrogels to be used as drug delivery system. The swelling behavior of freeze-dried hydrogels in aqueous media at different temperature and pHs has been examined. The swelling, porosity and biocompatibility behavior of samples were investigated to check effects of polymer/polymer and polymer/drug interactions on these system characteristics. Obtained experimental results illustrates that with increasing crosslinking agent from 0.068 to 0.30, swelling of the prepared samples degrees from 1200% to 600% and pore diameters change from 100 to 500 μm. To investigate systems biocompatibility in gastric... 

    Immobilization of α -chymotrypsin on the surface of magnetic/gold core/shell nanoparticles

    , Article Journal of Nanotechnology ; Volume 2013 , 2013 ; 16879503 (ISSN) Kamal Ahmadi, M ; Vossoughi, M ; Sharif University of Technology
    Hindawi Publishing Corporation  2013
    Over the last decade, nanoparticles used as protein carriers have opened new avenues for a variety of biomedical applications. The main concern for these applications is changes in biological activity of immobilized proteins due to conformational changes on the surface of the carrier. To evaluate this concern, the preparation and biocatalyst activity of α-chymotrypsin-Fe 3O4 @ Au core/shell nanoparticles were investigated. First, Fe3O4 @ Au core/shell nanoparticles were synthesized by coprecipitation method and citrate reduction of HAuCl 4. TEM imaging revealed a core size of 13 ± 3 nm and a shell thickness of 4 ± 1 nm for synthesized nanoparticles. X-ray diffraction (XRD) was used to study... 

    Lipase immobilisation on magnetic silica nanocomposite particles: Effects of the silica structure on properties of the immobilised enzyme

    , Article Journal of Materials Chemistry ; Volume 22, Issue 17 , 2012 , Pages 8385-8393 ; 09599428 (ISSN) Kalantari, M ; Kazemeini, M ; Tabandeh, F ; Arpanaei, A ; Sharif University of Technology
    Uniformly sized superparamagnetic single-shell nonporous (S1) and double-shell mesoporous silica nanocomposite particles with ∼130 nm magnetite cluster cores are synthesised in this study. Mesoporous particles are prepared with two BJH pore sizes (2.44 and 3.76 nm, designated as S2 and S3 particles, respectively). Once the lipase was immobilised on particles, our results showed that the enzyme loading capacities of mesoporous structures, i.e. S2 and S3, are higher than that for nonporous particles (S1). Hydrolytic activity tests reveal that immobilised lipases retain about 90% of the free enzyme's activity. Furthermore, comparing to the free enzyme, the thermal stability of immobilised... 

    Production of glucoamylase by aspergillus niger under solid state fermentation

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 25, Issue 1 , 2012 , Pages 1-7 ; 1728-144X (ISSN) Nahid, P ; Vossoughi, M ; Roostaazad, R ; Ahmadi, M ; Zarrabi, A ; Hosseini, S. M ; Sharif University of Technology
    In this study, Glucoamylase production by Aspergillus niger was investigated under solid state fermentation using low cost by-products of agricultural processes as substrate. Highest enzyme production was observed when a combination of wheat bran (WB) and corn flour (CF) was used as compared to WB+ rice bran, WB+ rice flour and WB alone. Several compositions of corn flours were experimented. The best combination of WB in addition of 10% corn flour resulted maximum enzyme activities. Study of the fermentations in flasks revealed 373.3 IU/gds and 41.4 g/l for the enzyme activity and protein concentration respectively under conditions of 30± 1°C, pH 4.7 and time 96 h. Optimum conditions... 

    Production of l-asparaginase from Escherichia coli ATCC 11303: Optimization by response surface methodology

    , Article Food and Bioproducts Processing ; Volume 89, Issue 4 , Oct , 2011 , Pages 315-321 ; 09603085 (ISSN) Kenari, S. L. D ; Alemzadeh, I ; Maghsodi, V ; Sharif University of Technology
    This paper discusses the studies carried out for the optimal production of enzyme l-asparaginase (l-asparagine amidohydrolase, EC from Escherichia coli (ATCC 11303). It was found that inoculum age of 18 h and inoculum size of 10% were the most favorable operating conditions for enzyme production. Lactose, yeast extract and KH 2PO 4 were found to be the best carbon, nitrogen and ion sources, respectively. Statistical method was used to survey how various medium conditions affect the enzyme production. By response surface methodology, the values of lactose, tryptone, yeast extract, KH 2PO 4 and l-asparagine concentration were investigated to obtain the maximum enzyme activity. The... 

    Purification and zymography of lipase from aspergillus Niger PTCC5010

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 28, Issue 8 , 2015 , Pages 1115-1123 ; 1728-144X (ISSN) Ghamari, M ; Alemzadeh, I ; Tabatabaee Yazdi, F ; Vossoughi, M ; Varidi, M ; Sharif University of Technology
    Materials and Energy Research Center  2015
    In this study, Lipase from Aspergillus Niger after extraction of medium culture was precipitated with different percentages of acetone and purified by ion exchange chromatography using SP-Sepharose HP and Q-Sepharose HP. The process of purification of the enzyme was studied by electrophoresis and the molecular weight was detected and determined by Zymography using overlying containing phenol red and Rhodamine B. The results showed that the vast majority of lipase from this strain has been precipitated by 70% saturation acetone, and leads to the 1.67 fold the purified enzyme, with special activities 32.8 U. mg-1 and efficiency of 38.5%. Using two-phase chromatography, enzyme specific activity... 

    Molecular interaction between three-dimensional graphene aerogel and enzyme solution: effect on enzyme structure and function

    , Article Journal of Molecular Liquids ; Volume 265 , 2018 , Pages 565-571 ; 01677322 (ISSN) Ehtesabi, H ; Bagheri, Z ; Eskandari, F ; Ahadian, M. M ; Sharif University of Technology
    New membrane materials and processes have been extensively developed due to urgent needs for much more economic separation processes. Recently, graphene has been confirmed to be an excellent separation membrane. As there is no support in the obtained three-dimensional (3D) architecture constructed from tubular graphene network, it is possible to take full advantage of the large surface of graphene. In this study 3D graphene aerogels were synthesized by a simple method and modified to adjust hydrophilicity of the samples to achieve high liquid volumetric rate. Modified samples were used for the filtration of the enzymes including amylase, cellulase, lipase and protease. Slightly differently...