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Total 296 records

    Optimization of Mucor miehei rennin production and recovery

    , Article Scientia Iranica ; Volume 9, Issue 1 , 2002 , Pages 99-104 ; 10263098 (ISSN) Kazemi Vaysari, A ; Kheirolomoom, A ; Arjmand, M ; Habibollahi, M ; Sharif University of Technology
    Sharif University of Technology  2002
    Abstract
    In this paper, fungal rennin production has been carried out by solid state fermentation of Mucor miehei NRRL 3420. The optimum dilution ratio, temperature and fermentation time of the enzymatic solution were determined to be 1:30, 40°C and 4 days after the beginning of the fermentation process, respectively. Also, the enzyme recovery by precipitation was studied using (NH4)2SO4, acetone and ethanol, respectively. The effects of pH, salt and solvent concentration on rennin recovery were studied and the optimum pH value as well as the optimum salt concentration were determined. The maximum specific activity of the enzyme was obtained by precipitation at pH of 6.5 and 50% saturated solution 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)
    Abstract
    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... 

    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
    Abstract
    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... 

    Application of an optimization algorithm for estimating intrinsic kinetic parameters of immobilized enzymes

    , Article Journal of Bioscience and Bioengineering ; Volume 94, Issue 1 , 2002 , Pages 1-7 ; 13891723 (ISSN) Khorasheh, F ; Kheirolomoom, A ; Mireshghi, S ; Sharif University of Technology
    Society of Fermentation and Bioengineering  2002
    Abstract
    A simple optimization methodology is applied to estimate the intrinsic kinetic parameters for both reversible and irreversible unireactant immobilized enzyme systems that follow the Michaelis-Menten mechanism. The method utilizes a direct-search optimization algorithm along with the numerical solution of the governing differential equations. The usefulness and validity of the method is demonstrated by comparing the predicted values of the intrinsic kinetic constants using the proposed method with a series of experimental values reported in the literature for different immobilized enzyme systems with irreversible and reversible reactions  

    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
    2013
    Abstract
    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... 

    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
    Abstract
    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... 

    Influence of phosphate anions on the stability of immobilized enzymes. Effect of enzyme nature, immobilization protocol and inactivation conditions

    , Article Process Biochemistry ; Volume 95 , August , 2020 , Pages 288-296 Kornecki, J. F ; Carballares, D ; Morellon Sterling, R ; Siar, E. H ; Kashefi, S ; Chafiaa, M ; Arana Peña, S ; Rios, N. S ; Gonçalves, L. R. B ; Fernandez Lafuente, R ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    A destabilizing effect at pH 7 of sodium phosphate on several lipases immobilized via interfacial activation is shown in this work. This paper investigates if this destabilizing effect is extended to other inactivation conditions, immobilization protocols or even other immobilized enzymes (ficin, trypsin, β-galactosidase, β-glucosidase, laccase, glucose oxidase and catalase). As lipases, those from Candida antarctica (A and B), Candida rugosa and Rhizomucor miehei have been used. Results confirm the very negative effect of 100 mM sodium phosphate at pH 7.0 for the stability of all studied lipases immobilized on octyl agarose, while using glutaraldehyde-support the effect is smaller (still... 

    Studing the Performance of Rotary Dryer in Drying Enzyme Products

    , M.Sc. Thesis Sharif University of Technology Azadi, Mostafa (Author) ; Roosta Azad, Reza (Supervisor)
    Abstract
    Drying is one of the important downstream processes in the production of biotechnological products. The dryer design for heat-sensitive materials such as proteins requires special process considerations. In this study, a rotary dryer evaluated for drying protein products. The used liquid enzyme as model, a bacterial α-amylase, first, immobilized on sodium sulfate and sodium tripolyphosphate as carriers in a spraying mode and then, the obtained wet solid materials containing the enzyme, dried in a batch dryer. The performance of this dryer investigated to achieve suitable properties such as the enzyme activity and the final moisture content of product by changing the process conditions.... 

    Study on Biodiesel Production Using Engineered Lipases

    , M.Sc. Thesis Sharif University of Technology Char Roostaei, Hamzeh (Author) ; Kazemeini, Mohammad (Supervisor)
    Abstract
    Biodiesel has drawn the attention of many researches to itself as a replacing source for crude oil, recently. Transesterification is one of the most popular methods used for biodiesel production. Enzyme transesterification is a more simple method in comparison with acidic or basic transesterification. However, the high price and low yield of enzyme transesterification has caused many obstacles in its application. Enzyme engineering has gained much attention as a way to improve enzyme performance. In this thesis, biodiesel production by a native enzyme named Bacillus thermocatenulatus, and two engineered-enzymes is studied. First, effective parameters and variables in biodiesel production by... 

    Investigating the Performance of Fluidized bed Dryer in Immobilization and Drying of A-amylase Enzyme

    , M.Sc. Thesis Sharif University of Technology Sharifi, Baha (Author) ; Roostaazad, Reza (Supervisor)
    Abstract
    Enzyme immobilization/drying operations are among the important operations of many biotechnological industrial units. The enzyme used in this study is bacterial alpha-amylase, which is widely used in various industries, including detergents. The production of alpha-amylase enzyme contains a large percentage of water in its composition; therefore, a wet wall tower was designed to conduct the experiments to evaporate the water present in the enzyme liquor, analyze its effects on activity, and also to validate the device. The results showed that in a flow of air around 240m3/hr and ambient temperature of 20◦C, enzyme liquor has a 250% increase in biological activity, which indicates the... 

    Magnetic labelled horseradish peroxidase-polymer nanoparticles: A recyclable nanobiocatalyst

    , Article Journal of the Serbian Chemical Society ; Volume 78, Issue 7 , 2013 , Pages 921-931 ; 03525139 (ISSN) Khosravi, A ; Vossoughi, M ; Shahrokhian, S ; Alemzadeh, I ; Sharif University of Technology
    2013
    Abstract
    In this study, the reusability and process stability of nano-reengineered horseradish peroxidase was investigated in a fluorescence-based sensing system for hydrogen peroxide determination as a model application. To this end, dendron macromolecules were attached to the enzyme surface through bio-conjugation techniques. The resulting enzyme-polymer nanoparticles, with an average size of 14(±2) nm, showed significant life time and thermal stability. For enzyme recovery and reusability purposes, the enzyme-polymer nanoparticles were labelled with magnetic nanoparticles with a labelling yield of 90 %. These labelled enzyme molecules showed significant process stability, i.e., up to 7 recycling... 

    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
    2012
    Abstract
    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... 

    The effect of endurance training with cinnamon supplementation on plasma concentrations of liver enzymes (ALT,AST) in women with type II diabetes

    , Article Tehran University Medical Journal ; Volume 74, Issue 6 , 2016 , Pages 433-441 ; 16831764 (ISSN) Torabi, S ; Asad, M. R ; Tabrizi, A ; Sharif University of Technology
    Tehran University of Medical Sciences  2016
    Abstract
    Background: Diabetes is associated with many pathological changes and one of the most important consequences of the diabetes is hepatic injury. The present study was performed to investigate the effect of eight weeks endurance training with consumption of cinnamon supplementation on plasma concentrations of liver enzymes,alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in women with type II diabetes. Methods: In this quasi-experimental study,36 female volunteers with type II diabetes (age 52.72±2.64 years and body mass index 29.28±2.94 Kg/m2) were participated. The subjects were homogenized regarding their body mass index and then were divided randomly into four groups... 

    Enzymatic formation of recombinant antibody-conjugated gold nanoparticles in the presence of citrate groups and bacteria

    , Article Catalysts ; Volume 12, Issue 9 , 2022 ; 20734344 (ISSN) Rad, M ; Ebrahimipour, G ; Bandehpour, M ; Akhavan, O ; Yarian, F ; Sharif University of Technology
    MDPI  2022
    Abstract
    With the spread of deadly diseases worldwide, the design of rapid tests to identify causative microorganisms is necessary. Due to the unique properties of gold nanoparticles, these nanoparticles are used in designing rapid diagnostic tests, such as strip tests. The current study aimed to investigate the ability of gold nanoparticles to bind to single-chain variable fragment antibodies. In this study, the biological and chemical methods included Escherichia coli TOP-10 and the Turkevich method to synthesize the gold nanoparticles, respectively. Then, the effect of synthetic nanoparticles on their capability of binding to recombinant antibodies was assessed by agarose gel and UV-vis... 

    Experimental Studies for Lactase Immobilization on the Polymer base and Characterising

    , M.Sc. Thesis Sharif University of Technology Derakhshan, Elahe (Author) ; Yaghmaei, Soheyla (Supervisor)
    Abstract
    Immobilization of β-D-galactosidase represents an important approach for development of lactose hydrolysis technology.Chitosan proved to be an excellent carrier for β-Dgalactosidase immobilization, by both covalent binding and sol-gel entrapment combined with adsorption. Among different preparation methods of chitosan support particles for covalent binding, emulsion cross-linking was the most efficient, producing narrow-sized microspheres, without aggregation.The best process parameters of β-D-galactosidase immobilization by covalent coupling on chitosan microspheres were found as 3% glutaraldehyde cross-linker concentration, enzyme loading of 27 mg protein/g dry support, 6 h reaction time,... 

    Covalent immobilization of cellulase using magnetic poly(ionic liquid) support: improvement of the enzyme activity and stability

    , Article Journal of Agricultural and Food Chemistry ; Volume 66, Issue 4 , 2018 , Pages 789-798 ; 00218561 (ISSN) Hosseini, H ; Hosseini, A ; Zohreh, N ; Yaghoubi, M ; Pourjavadi, A ; Sharif University of Technology
    American Chemical Society  2018
    Abstract
    A magnetic nanocomposite was prepared by entrapment of Fe3O4 nanoparticles into the cross-linked ionic liquid/epoxy type polymer. The resulting support was used for covalent immobilization of cellulase through the reaction with epoxy groups. The ionic surface of the support improved the adsorption of enzyme, and a large amount of enzyme (106.1 mg/g) was loaded onto the support surface. The effect of the presence of ionic monomer and covalent binding of enzyme was also investigated. The structure of support was characterized by various instruments such as FT-IR, TGA, VSM, XRD, TEM, SEM, and DLS. The activity and stability of immobilized cellulase were investigated in the prepared support. The... 

    Phenols removal by immobilized horseradish peroxidase

    , Article Journal of Hazardous Materials ; Volume 166, Issue 2-3 , 2009 , Pages 1082-1086 ; 03043894 (ISSN) Alemzadeh, I ; Nejati, S ; Sharif University of Technology
    2009
    Abstract
    Application of immobilized horseradish peroxidase (HRP) in porous calcium alginate (ca-alginate) for the purpose of phenol removal is reported. The optimal conditions for immobilization of HRP in ca-alginate were identified. Gelation (encapsulation) was optimized at 1.0% (w/v) sodium alginate in the presence of 5.5% (w/v) of calcium chloride. Upon immobilization, pH profile of enzyme activity changes as it shows higher value at basic and acidic solution. Increasing initial phenol concentration results in a decrease in % conversion. The highest conversion belongs to phenol concentration of 2 mM. Investigation into time course of phenol removal for both encapsulated and free enzymes showed... 

    Evaluation of biodiesel production using lipase immobilized on magnetic silica nanocomposite particles of various structures

    , Article Biochemical Engineering Journal ; Volume 79 , 2013 , Pages 267-273 ; 1369703X (ISSN) Kalantari, M ; Kazemeini, M ; Arpanaei, A ; Sharif University of Technology
    2013
    Abstract
    Nonporous and mesoporous silica-coated magnetite cluster nanocomposites particles were fabricated with various silica structures in order to develop a desired carrier for the lipase immobilization and subsequent biodiesel production. Lipase from Pseudomonas cepacia was covalently bound to the amino-functionalized particles using glutaraldehyde as a coupling agent. The hybrid systems that were obtained exhibited high stability and easy recovery regardless of the silica structure, following the application of an external magnetic field. The immobilized lipases were then used as the recoverable biocatalyst in a transesterification reaction to convert the soybean oil to biodiesel with methanol.... 

    The Use of Flavin Reductase Enzyme as Biocatalyst in Promiscuous Catalyzing Organic Reactions and Investigating Amyloid Inhibition in Proteins Using Aromatic Compounds

    , M.Sc. Thesis Sharif University of Technology Masihzadeh, Zahra (Author) ; Kalhor, Hamid Reza (Supervisor)
    Abstract
    Enzymes are proteins that carry out chemical reactions in the form of chemo, stereo, and regioselective under mild conditions. One of the characteristics of enzymes is that they perform a specific chemical reaction on a selective substrate and under specific environmental conditions. However, in recent years, a number of enzymes have been identified to display promiscous behavior. This promiscousity includes catalytic activity, variety of substrates, and environmental conditions. Promiscous activities of enzymes can be a good starting point for creating new and more favorable engineered pathways for the production of chemical and medicinal drugs. One of the aims of this project is to exploit...