Search for: amino-acids
Total 128 records
Article BioSystems ; Volume 77, Issue 1-3 , 2004 , Pages 163-173 ; 03032647 (ISSN) ; Nejad, H. A ; Torabi, N ; Sharif University of Technology
The existence of nonrandom patterns in codon assignments is supported by many statistical and biochemical studies. The canonical genetic code is known to be highly efficient in minimizing the effects of mistranslation errors and point mutations. For example, it is known that when an error induces the conversion of an amino acid to another, the biochemical properties of the resulting amino acid are usually very similar to that of the original. Prior studies include many attempts at quantitative estimation of the fraction of randomly generated codes which, based upon load minimization, score higher than the canonical genetic code. In this study, we took into consideration both the relative...
Article Journal of Chemical Thermodynamics ; Volume 35, Issue 1 , 2003 , Pages 101-112 ; 00219614 (ISSN) ; Ghotbi, C ; Taghikhani, V ; Sharif University of Technology
A new two-parameter model based on the perturbation of a hard-sphere reference has been developed to correlate the activity coefficients of several amino acids and simple peptides in aqueous solutions. The hard-sphere equation of state used as the reference in the model was proposed recently by Ghotbi and Vera. The perturbation terms coupled with the reference hard-sphere equation of state are attributed to the dispersion forces and the dipole-dipole interactions. The Lennard-Jones and Keesom potential functions are used to represent the dispersion and dipole-dipole interactions, respectively. The results of the new model are compared with those obtained by other models. It is shown that the...
Synthesis, characterization, and application of a new tripodal ligand for the preparation of LSCF(6482) perovskite, Article Chemical Papers ; Vol. 68, issue. 7 , 2014 , p. 989-994 ; Ghanbari, B ; Hajibabaei, H ; Sharif University of Technology
The main aim of this paper was to study the effect of a new tripodal chelating agent on La1-x Sr x Co1-y Fe y O3-δ perovskite prepared by the complexation method. For this purpose, a phenolic derivative of glycine (L) was synthesized applying the Mannich reaction and characterized by NMR and IR spectroscopies as well as by elemental analysis. To evaluate the complexation capability of L, its formation constants with the perovskite cations were measured. Comparison of these results with those reported for the complexaion with glycine, introduced L as a good candidate for the complexation with Fe(III) and La(III) cations. Furthermore, the powder XRD observations confirmed an improvement in the...
Synthesis, X-ray structure and ascorbic oxidation properties of ternary α-amino acid Schiff base-bipy Cu(II) complexes as functional models for ascorbic oxidase, Article Polyhedron ; Volume 53 , 2013 , Pages 76-82 ; 02775387 (ISSN) ; Amini, Z ; Boghaei, D. M ; Notash, B ; Sharif University of Technology
Three ternary copper(II) complexes [Cu(5-bromo-salTyr)(bipy)]·1/ 2CH3OH (1), [Cu(5-bromo-salLue)(bipy)]·CH3OH (2) and [Cu(5-bromo-salTrp)(bipy)]·3CH3OH (3) (where 5-bromo-salTyr, 5-bromo-salLue and 5-bromo-salTrp are tridentate Schiff base ligands derived from the condensation of 5-bromosalicylaldehyde with tyrosine, leucine and tryptophan, respectively, and bipy is 2,2′-bipyridine) have been prepared and characterized by elemental analysis, electronic, IR spectroscopies, magnetic measurement and cyclic voltammetry. The complexes, 1 and 3 have been also structurally characterized by X-ray diffraction technique. Crystal structures of 1 and 3 complexes displayed a distorted square-pyramidal...
Measurement of activity coefficients of amino acids in aqueous electrolyte solutions: Experimental data for the systems (H2O + NaBr + glycine) and (H2O + NaBr + L-valine) at T = 298.15 K, Article Journal of Chemical Thermodynamics ; Volume 35, Issue 9 , 2003 , Pages 1553-1565 ; 00219614 (ISSN) ; Modarress, H ; Taghikhani, V ; Khoshkbarchi, M. K ; Sharif University of Technology
Academic Press 2003
Electrochemical cells with two ion-selective electrodes, a cation ion-selective electrode against an anion ion-selective electrode, were used to measure the activity coefficient of amino acids in aqueous electrolyte solutions. Activity coefficient data were measured for (H2O + NaBr + glycine) and (H2O + NaBr + L-valine) at T = 298.15 K. The maximum concentrations of sodium bromide, glycine, and L-valine were (1.0, 2.4, and 0.4) mol · kg-1, respectively. The results show that the presence of an electrolyte and the nature of both the cation and the anion of the electrolyte have significant effects on the activity coefficients of amino acid in aqueous electrolyte solutions
Activity coefficients of electrolyte and amino acid in the systems (water + potassium chloride + DL-valine) at T = 298.15 K and (water + sodium chloride + L-valine) at T = 308.15 K, Article Journal of Chemical Thermodynamics ; Volume 34, Issue 8 , 2002 , Pages 1297-1309 ; 00219614 (ISSN) ; Modarress, H ; Taghikhani, V ; Khoshkbarchi, M. K ; Sharif University of Technology
The activity coefficient data were reported for (water + potassium chloride + DL-valine) at T = 298.15 K and (water + sodium chloride + L-valine) at T = 308.15 K. The measurements were performed in an electrochemical cell using ion-selective electrodes. The maximum concentrations of the electrolytes and the amino acids studied were 1.0 molality and 0.4 molality, respectively. The results of the activity coefficients of DL-valine are compared with the activity coefficients of DL-valine in (water + sodium chloride + DL-valine) system obtained from the previous study. The results show that the presence of an electrolyte and the nature of its cation have a significant effect on the activity...
Article Polymers for Advanced Technologies ; Volume 20, Issue 8 , 2009 , Pages 655-671 ; 10427147 (ISSN) ; Pourjavadi, A ; Salimi, H ; Kurdtabar, M ; Sharif University of Technology
The use of super-swelling polymers is steadily increasing and the applications in industry are continuing to grow. With the authorization of the superabsorbents in food packaging by the Food and Drug Administration recently, demand may soon take off in the market. However, the increase in prices of petroleum products in recent years may be a drawback for these acrylic-based materials. Thus, there is now a need to develop natural-based super-swelling hydrogels which are more economical and environment friendly. In addition, the super-swelling gels are promising novel functions in the biomedical and pharmaceutical applications. This review is aimed to highlight research and trends in protein-...
Article Bulletin of Mathematical Biology ; Volume 67, Issue 6 , 2005 , Pages 1355-1368 ; 00928240 (ISSN) ; Shateri Najafabadi, H ; Ahmadi Nejad, H ; Torabi, N ; Sharif University of Technology
Statistical and biochemical studies have revealed nonrandom patterns in codon assignments. The canonical genetic code is known to be highly efficient in minimizing the effects of mistranslational errors and point mutations, since it is known that, when an amino acid is converted to another due to error, the biochemical properties of the resulted amino acid are usually very similar to those of the original one. In this study, we have taken into consideration both relative frequencies of amino acids and relative gene copy frequencies of tRNAs in genomic sequences in order to introduce a fitness function which models the mistranslational probabilities more accurately in modern organisms. The...
M.Sc. Thesis Sharif University of Technology ; Dolati, Abolghasem
Gold coatings due to their unique properties, use in a wide range of applications.Decorative coatings of gold for centuries, has been considered.However, few studies have been done on the properties of this metal, this metal is shown not only in terms of decorating, but in the industry also has a wide range of applications. In this project non-cyanide electroless bath based on binary complex sulfite-thiosulfate was prepared and metal ion concentration of the complex components, temperature, time, pH and addition of amino acids, optimzed bystability, qualityand rate of coating. The main aim of optimizing bathsis optimize the thickness and appearance of the coating.It was found that by...
Synthesis and Application of Aminophenolic Ligands in Preparation of Perovskite-type Inorganic Membranes, M.Sc. Thesis Sharif University of Technology ; Ghanbari, Bahram
Inorganic membranes are a group of compounds which are used in gas separations such as isolating of oxygen from air and/or in petrochemical process like OCM, POM. These days, a variety of research is being conducted to synthesize these membranes from perovskite structures with formulation of ABO3. These compounds have various production procedures and various final perovskite compounds. The purpose of this project is to synthesis and identification of a group of phenolic amino acidic derivatives as new chelating agents, and their use in synthesis of perovskite membranes. For this, novel phenol derivatives of glycine, alanine, β- alanine and leucine amino acids were synthesized and...
Synthesis and characterization of water-soluble zinc(II) Schiff-base complexes derived from amino acids and 3-formyl-4-hydroxybenzyl- triphenylphosphonium chloride, Article Journal of Coordination Chemistry ; Volume 61, Issue 12 , 2008 , Pages 1917-1926 ; 00958972 (ISSN) ; Askarizadeh, E ; Sharif University of Technology
Tridentate Schiff-base ligands derived from condensation of 3-formyl-4-hydroxybenzyl-triphenylphosphonium chloride with glycine, L-alanine, L-valine, L-leucine and L-phenylalanine in the presence of Zn(OAc)2·2H2O form five new water-soluble Zn(II) complexes, which were characterized by elemental analyses, IR, electronic absorption and 1H, 13C NMR spectroscopies. In the IR spectra of the complexes, the difference between the asymmetric and the symmetric carboxylate stretching frequencies is larger than ∼210 cm-1, which implies that the carboxylate groups are monodentate. UV-Vis electronic absorption studies show that Zn(II) functions as a trap for the Schiff-base intermediate. Schiff-base...
Synthesis and characterization of novel water-soluble zinc(II) Schiff-base complexes derived from amino acids and salicylaldehyde-5-sulfonates, Article Journal of Coordination Chemistry ; Volume 60, Issue 3 , 2007 , Pages 339-346 ; 00958972 (ISSN) ; Gharagozlou, M ; Sharif University of Technology
New water-soluble zinc(II) Schiff-base complexes derived from amino acids (glycine, L-phenylalanine, and L-valine) and salicylaldehyde-5-sulfonates (sodium salicylaldehyde-5-sulfonate and sodium 3-methoxy-salicylaldehyde-5- sulfonate) have been synthesized. The complexes were characterized by elemental analysis, IR, electronic, 1H NMR, and 13C NMR spectra. In the IR spectra of the complexes, the large difference between the asymmetric νas(COO) and symmetric νs(COO) carboxylate stretch, Δν(νas(COO)-νs(COO)) of 199-247 cm-1, indicates monodentate coordination of the carboxylate group. Spectral data showed that in these complexes the ligand is a tridentate ONO moiety, coordinating to the metal...
M.Sc. Thesis Sharif University of Technology ; Gholami, Mohammad Reza
Nanosized CdS coupled TiO2 nanocrystals were prepared by a microemulsion-mediated Hydrothermal method at relatively low temperatures. Modification of this nanocomposite with Tyrosine,Phenylalanine,Glysine and Glutamate ,especially Tyrosine resulted in enhanced photocatalytic degradation rate of Nitrobenzene( NB ) compared to using CdS-TiO2 under visible light irradiation. The prepared samples were characterized by BET,SEM, XRD, UV–Vis spectroscopy ,FTIR .It was found which have high surface area about 470 m2 g−1 and mesoporous character with the average pore diameter of 2.8 nm.The results showed this nanocomposite consisted of uniform anatase TiO2 with highly dispersed cubic phase CdS...
M.Sc. Thesis Sharif University of Technology ; Ghanbari, Bahram
The purpose of this project is the synthesis and characterization of a group of phenolic amino acidic derivatives that are studied in both solid phases as well as their solutions. For this, new phenol derivatives of serin and isoleucine amino acids were synthesized and characterized by 1H NMR , 13C NMR, IR spectroscopy as well as elemental analysis. These ligands were utilized to prepare LSF perovskite membrane. According to their XRD patterns, it was concluded that the powdered precursor prepared by serin derivative has shown better qualification and less intermediate phase in the synthesized perovskite membrane similar to the sample prepared by applying EDTA. Furthermore, in the previous...
Influence of the water molecules (n 5 1-6) on the interaction between Li +, Na +, K + cations and indole molecule as tryptophan amino acid residue, Article Structural Chemistry ; Volume 23, Issue 3 , 2012 , Pages 857-865 ; 10400400 (ISSN) ; Nasiri, M ; Fattahi, A ; Vafaeezadeh, M ; Sharif University of Technology
Influence of the addition of water molecules (n = 1-6) on the interaction energy between Li +, Na +, K + cations and indole molecule as tryptophan amino acid residue is considered at MP2(FULL)/6-311++G(d, p)//B3LYP/6-311++G(d,p) levels of theory. The calculations suggest that the size of cation and the number of water molecules are two important factors that affect the interaction energy between the hydrated metal cation and indole molecule. The strength of cation-π interactions get substantially reduced when the metal ion is solvated or the size of metal cation increases. Quantum theory of atoms in molecules analysis of cation-π interaction indicates that there is a correlation between the...
Correlation and prediction the activity coefficients and solubility of amino acids and simple peptide in aqueous solution using the modified local composition model, Article Fluid Phase Equilibria ; Volume 255, Issue 2 , 2007 , Pages 160-166 ; 03783812 (ISSN) ; Taghikhani, V ; Vossoughi, M ; Sharif University of Technology
In this work, the modified Wilson model was used to obtain the activity coefficients of amino acids and simple peptides in non-electrolyte aqueous solutions. The Wilson model was modified using the new local mole fraction proposed by Zhao et al. and non-random case for the reference state. The binary interaction parameters (BIP) of the modified Wilson model for amino acid-water pairs were obtained using the experimental data of the activity coefficients for amino acids available in the literature. The modified Wilson model was also used to correlate the solubility of amino acids in water and the values of Δh/R, Δs/R, and Δg/R of the solutions studied were reported. The results obtained...
Article Physical Review Letters ; Volume 93, Issue 20 , 2004 , Pages 208105-1-208105-4 ; 00319007 (ISSN) ; Ejtehadi, M. R ; Plotkin, S. S ; Sharif University of Technology
American Physical Society 2004
The folding rates of protein were shown to correlate with the degree of heterogeneity in the formation of native contacts. It was shown that both experimental rates and simulated free energy barriers for 2-state proteins depend on the degree of heterogeneity present in the folding process. Heterogeneity due to variance in the distribution of native loop lengths, and variance in the distribution of φ values, were observed to increase folding rates and reduce folding barriers. The observed effect due to φ variance was found to be the most statistically significant, because φ variance captures both heterogeneity arising from native topology and that arising from energetics
Article World Journal of Microbiology and Biotechnology ; Volume 26, Issue 5 , 2010 , Pages 871-878 ; 09593993 (ISSN) ; Maghsoudi, E ; Roostaazad, R ; Dadafarin, H ; Sahebghadam Lotfi, A ; Amoozegar, M. A ; Sharif University of Technology
The physical properties and chemical structure of a new biosurfactant (licheniformin) produced by Bacillus licheniformis MS3 were investigated. The purified biosurfactant was identified as a lipopeptide with amino acid sequence of Gly, Ala, Val, Asp, Ser, Gly, Tyr and a lactone linkage between the carboxyl group of Aspargine and hydroxyl group of Tyrosine residue. The fatty acid moiety was attached to N-terminal amino acid residue through an amide bond. The purified licheniformin could lower the surface tension of water from 72 to 38 mN/m at concentrations higher than 15 μg/mL and its relative emulsion volume (EV%) was equal to 36%. It also showed stable surface activity over a wide range of...
Expression and Purification of Amyloid Beta Recombinant Peptide and the Effecs of Ultrasmall Peptides Enriched in Branch Chain Amino Acids as Inhibitors in Amyloid Formation, M.Sc. Thesis Sharif University of Technology ; Kalhor, Hamid Reza
Nowdays, it has been shown that protein misfolding is involved in more than forty diseases including Alzheimer’s and Parkinson’s. Alzheimer’s disease is one of the most common neurodegenerative diseases that disrupts brain function. The main cause of this illness is due to formation of extracellular amyloid plaque from a 42-amino acid-peptide called amyloid beta. Amyloidosis is caused by missfolding of peptides and proteins mainly because of physical and chemical changes in biomolecule or their environment.
Therefore, in this dissertation, using synthetic and recombinant abeta peptide, kinetic of amyloidosis was examined. Ultrasmall peptides (three-amino acid), containing branched chain...
Therefore, in this dissertation, using synthetic and recombinant abeta peptide, kinetic of amyloidosis was examined. Ultrasmall peptides (three-amino acid), containing branched chain...
M.Sc. Thesis Sharif University of Technology ; Ghotbi, Cyrus ; Taghikhani, Vahid ; Vosoghi, Manochehr
In this work, partitioning of amino acids such as glutamic acid, phenyl anine and tryptophan in aqueous and ionic liquid phases at 298.15 K and atmospheric pressure was measured. [C4mim][Tf2N] is used due can produce two phase with water rapidly. Studying the effect of liquid solution pH on amino acids partitioning shows that increasing of pH results in decreasing of amino acid partitioning coefficient. This phenomenon pertains to electrostatic interactions between cation of amino acid and anion of ionic liquid which reduces when pH increases. Considering the effect of pH, liquid-liquid equilibrium data of amino acids was obtained in a pH that owning maximum partioning coefficient. Chemical...