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Papers by A. Hambardumyan
Bardzr tekhnologianeri teghekagir, Jun 28, 2024
In this study we present novel methodology for studying the interaction of biologically active su... more In this study we present novel methodology for studying the interaction of biologically active substances with ion channels reconstructed in bilayer lipid membranes (BLM). We utilized reconstruction of grasshopper Na+ channels in planar BLM and cyclic voltammetric technology for this purpose. BLM constructed from general lipids of bovine brain shows in NaCl as well in KCl solution a typical curve of cyclic voltammetry. In BLM reconstructed with grasshopper cephalothorax membrane proteins the capacitance and the resistance shifted to 2.2 μF/cm2 and 160 MΩ (against to 0.2 μF/cm2 and 1.3 GΩ for BLM free from membrane proteins), respectively, for BLM prepared in 1 mm diameter hole in NaCl solution, while remaining constant in KCl. The results indicate about insect sodium channels reconstruction in BLM. We used the developed methodology for determination of apparent dissociation constant (K’d) of ligand-macromolecule interaction for the model of pyrethroid insecticide and ion-channel. Th...
European Food Research and Technology, 2021
Recently, there has been a revival of interest in the use of natural pigments in various industri... more Recently, there has been a revival of interest in the use of natural pigments in various industries. It is of great interest to obtain melanins from plant raw materials. An effective method has been developed for cleaning grape squeezes from impurities before the alkaline extraction of melanin. A schematic flow diagram of the isolation and purification of water-soluble melanin from grape squeezes is presented. The obtained pigment was identified by spectroscopic methods. It has been established by thermal treatment that the amorphous precipitate of melanin is stable at temperatures up to 120 °C, and the acid resistance of the obtained melanin solution is in the pH range of > 4.0. Gel filtration, electrophoresis and HPLC showed that the pigment preparation contained four fractions that differed by their molecular weights. The quantitative distribution and the molecular weights of the obtained melanin fractions were determined. Qualitative reactions and spectroscopic methods have shown that these fractions are typical melanins. The elemental composition of the obtained melanin and its antioxidant properties, the amino acid composition of the melanin protein, and its solubility were determined. The yield of melanin from the feedstock was 17.3%. Based on the physicochemical properties of the resulting melanin, it can be used as an effective natural food coloring and powerful antioxidant substance.
International Journal of Peptide Research and Therapeutics, 2021
Proline rich polypeptide 1 (PRP-1) was isolated from the neurosecretory granules of bovine neuroh... more Proline rich polypeptide 1 (PRP-1) was isolated from the neurosecretory granules of bovine neurohypophysis and thoroughly characterized by Professor A. Galoyan and coauthors. BLAST analyses of PRP-1 with proteins of protein data bank indicated, that it is the C-terminus of third constituent of pre-pro-arginine vasopressin – copeptin, for all studied mammal species, as showed Galoyan and coauthors for bovine case. Also, BLAST analyses indicated, that the amino acid motive of PRP-1 is conservative in the course of the evolution, and occurred among enzymes of prokaryotic and eukaryotic origin Obtained to date data indicate multiple functionalities of this polypeptide, through to its diverse modulatory actions on set of different receptors. Using the AutoDock vina software it was shown, that PRP-1 and its homologues strongly interact with receptors, such as: mouse phosphorylated mitogen activated protein kinase 14, mouse toll like receptor 4, human Ca-sensing receptor, human epithelial growth factor receptor and human superoxide dismutase 1. As these receptors play important role in multiple cell signaling processes, the importance of their ligand peptides and homologues is obvious. But it should be stated, that, through docking experiments although are very informative, they should be considered as supplementary to real physical experiments, which should be carried out with the same receptors.
High-Throughput, 2020
D-hydantoinases catalyze an enantioselective opening of 5- and 6-membered cyclic structures and t... more D-hydantoinases catalyze an enantioselective opening of 5- and 6-membered cyclic structures and therefore can be used for the production of optically pure precursors for biomedical applications. The thermostable D-hydantoinase from Geobacillus stearothermophilus ATCC 31783 is a manganese-dependent enzyme and exhibits low activity towards bulky hydantoin derivatives. Homology modeling with a known 3D structure (PDB code: 1K1D) allowed us to identify the amino acids to be mutated at the substrate binding site and in its immediate vicinity to modulate the substrate specificity. Both single and double substituted mutants were generated by site-directed mutagenesis at appropriate sites located inside and outside of the stereochemistry gate loops (SGL) involved in the substrate binding. Substrate specificity and kinetic constant data demonstrate that the replacement of Phe159 and Trp287 with alanine leads to an increase in the enzyme activity towards D,L-5-benzyl and D,L-5-indolylmethyl h...
Pigment Cell Research, 2005
Melanins are widely used in medicine, pharmacology, cosmetics and other fields. Although several ... more Melanins are widely used in medicine, pharmacology, cosmetics and other fields. Although several technologies for the purification of water-insoluble dioxyphenylalanine (DOPA) melanins have been described, a source of water-soluble melanin is highly desirable. Here we describe an effective procedure for the isolation and purification of water-soluble melanin using the culture medium of Bacillus thuringiensis subsp. galleriae strain K1. Water-soluble melanin from this organism has an isoelectric point (pI=3.0-3.2) and was purified optimally by adsorbtion using the IA-1r resin and elution as a concentrated solution. The purified melanin obtained exhibited a similar infra-red absorbtion spectrum to synthetic melanin and contained quinolic and phenolic structures and an amino acid content of around 20% after acid hydrolysis. The molecular weight of the purified melanin determined by SDS-PAGE was 4 kDa and the electromagnetic spin resonance spectrum of the purified microbial melanin was a slightly asymmetric singlet without hyperfine structure with about 7 Gauss width of the line between points of the maximum incline and g=2.006. The concentration of paramagnetic centers in melanin is 0.21x10(18) spin/g. The results obtained provide a rapid, simple and inexpensive method for the large scale purification of water soluble melanin that may have widespread applications.
Chemico-Biological Interactions, 2008
Scientific reports, Jan 17, 2016
Activation of cell signaling by reactive chemicals and pollutants is an important issue for human... more Activation of cell signaling by reactive chemicals and pollutants is an important issue for human health. It has been shown that lipophilic nitro-benzoxadiazole (NBD) compounds rapidly move across the plasma membrane and enhance Epidermal Growth Factor Receptor (EGFR) tyrosine phosphorylation in cancer cells. Unlike ligand-dependent activation, the mechanism of this induction relies on the generation of hydrogen peroxide, which is involved in the activation of the catalytic site of the receptor and the inactivation of protein tyrosine phosphatase PTP-1B. Production of H2O2 during redox transformation of NBD compounds is associated with the transition of a monomeric form of Cu/Zn superoxide dismutase 1 (SOD1) to stable dimers. The highly stable and functionally active SOD1 dimer, in the absence of adequate activities in downstream reactions, promotes the disproportionate production and accumulation of intracellular hydrogen peroxide shortly after exposure to NBD compounds. The intrin...
In this study we present novel methodology for studying the interaction of biologically active su... more In this study we present novel methodology for studying the interaction of biologically active substances with ion channels reconstructed in bilayer lipid membranes (BLM). We utilized reconstruction of grasshopper Na+ channels in planar BLM and cyclic voltammetric technology for this purpose. BLM constructed from general lipids of bovine brain shows in NaCl as well in KCl solution a typical curve of cyclic voltammetry. In BLM reconstructed with grasshopper cephalothorax membrane proteins the capacitance and the resistance shifted to 2.2 μF/cm2 and 160 MΩ (against to 0.2 μF/cm2 and 1.3 GΩ for BLM free from membrane proteins), respectively, for BLM prepared in 1 mm diameter hole in NaCl solution, while remaining constant in KCl. The results indicate about insect sodium channels reconstruction in BLM. We used the developed methodology for determination of apparent dissociation constant (K’d) of ligand-macromolecule interaction for the model of pyrethroid insecticide and ion-channel. Th...
Using multivariate linear regression approach, open-source scripts have been developed in Gauss 4... more Using multivariate linear regression approach, open-source scripts have been developed in Gauss 4.0. for the calculation of the kinetic parameters and their dispersions for the cases of competitive, none competitive, mixed and substrate inhibitions. The methods of derivation of corresponding equations of stationary kinetics, their linearization and derivation of analytic forms of kinetic parameters and their dispersions are presented.Կիրառելով բազմաչափ գծային ռեգրեսիայի մոտեցումը` Գաուս 4.0. լեզվով հանրամատչելի ծրագրեր են մշակվել մրցակցային, անմրցակից, խառը և սուբստրատային արգելակումների դեպքերում կինետիկական պարամետրերի և դրանց դիսպերսիաների հաշվարկման համար: Ներկայացվել են ստացիոնար կինետիկայի համապատասխան հավասարումների դուրս բերման, դրանց գծայնացման և կինետիկական պարամետրերի և դրանց դիսպերսիաների հավասարումների դուրս բերման մեթոդները:Используя подход многомерной линейной регрессии, были разработаны публично доступные программы на Gauss 4.0. для расчета кинетических параметров и ...
In this study we present novel methodology for studying the interaction of biologically active su... more In this study we present novel methodology for studying the interaction of biologically active substances with ion channels reconstructed in bilayer lipid membranes (BLM). We utilized reconstruction of grasshopper Na+ channels in planar BLM and cyclic voltammetric technology for this purpose. BLM constructed from general lipids of bovine brain shows in NaCl as well in KCl solution a typical curve of cyclic voltammetry. In BLM reconstructed with grasshopper cephalothorax membrane proteins the capacitance and the resistance shifted to 2.2 μF/cm2 and 160 MΩ (against to 0.2 μF/cm2 and 1.3 GΩ for BLM free from membrane proteins), respectively, for BLM prepared in 1 mm diameter hole in NaCl solution, while remaining constant in KCl. The results indicate about insect sodium channels reconstruction in BLM.
We used the developed methodology for determination of apparent dissociation constant (K’d) of ligand-macromolecule interaction for the model of pyrethroid insecticide and ion-channel. The resistance of BLM with reconstructed ion channels was used for quantitative characterization of mentioned interaction.
Determination of K’d values for ligand – ion channel complexes, using the asymptotic method of none-linear
regression analysis, reviled 40.3±8.7 μM and 104.9±16.9 μM for known pyrethroids deltamethrin and cypermethrin,
respectively.
Bardzr tekhnologianeri teghekagir, Jun 28, 2024
In this study we present novel methodology for studying the interaction of biologically active su... more In this study we present novel methodology for studying the interaction of biologically active substances with ion channels reconstructed in bilayer lipid membranes (BLM). We utilized reconstruction of grasshopper Na+ channels in planar BLM and cyclic voltammetric technology for this purpose. BLM constructed from general lipids of bovine brain shows in NaCl as well in KCl solution a typical curve of cyclic voltammetry. In BLM reconstructed with grasshopper cephalothorax membrane proteins the capacitance and the resistance shifted to 2.2 μF/cm2 and 160 MΩ (against to 0.2 μF/cm2 and 1.3 GΩ for BLM free from membrane proteins), respectively, for BLM prepared in 1 mm diameter hole in NaCl solution, while remaining constant in KCl. The results indicate about insect sodium channels reconstruction in BLM. We used the developed methodology for determination of apparent dissociation constant (K’d) of ligand-macromolecule interaction for the model of pyrethroid insecticide and ion-channel. Th...
European Food Research and Technology, 2021
Recently, there has been a revival of interest in the use of natural pigments in various industri... more Recently, there has been a revival of interest in the use of natural pigments in various industries. It is of great interest to obtain melanins from plant raw materials. An effective method has been developed for cleaning grape squeezes from impurities before the alkaline extraction of melanin. A schematic flow diagram of the isolation and purification of water-soluble melanin from grape squeezes is presented. The obtained pigment was identified by spectroscopic methods. It has been established by thermal treatment that the amorphous precipitate of melanin is stable at temperatures up to 120 °C, and the acid resistance of the obtained melanin solution is in the pH range of > 4.0. Gel filtration, electrophoresis and HPLC showed that the pigment preparation contained four fractions that differed by their molecular weights. The quantitative distribution and the molecular weights of the obtained melanin fractions were determined. Qualitative reactions and spectroscopic methods have shown that these fractions are typical melanins. The elemental composition of the obtained melanin and its antioxidant properties, the amino acid composition of the melanin protein, and its solubility were determined. The yield of melanin from the feedstock was 17.3%. Based on the physicochemical properties of the resulting melanin, it can be used as an effective natural food coloring and powerful antioxidant substance.
International Journal of Peptide Research and Therapeutics, 2021
Proline rich polypeptide 1 (PRP-1) was isolated from the neurosecretory granules of bovine neuroh... more Proline rich polypeptide 1 (PRP-1) was isolated from the neurosecretory granules of bovine neurohypophysis and thoroughly characterized by Professor A. Galoyan and coauthors. BLAST analyses of PRP-1 with proteins of protein data bank indicated, that it is the C-terminus of third constituent of pre-pro-arginine vasopressin – copeptin, for all studied mammal species, as showed Galoyan and coauthors for bovine case. Also, BLAST analyses indicated, that the amino acid motive of PRP-1 is conservative in the course of the evolution, and occurred among enzymes of prokaryotic and eukaryotic origin Obtained to date data indicate multiple functionalities of this polypeptide, through to its diverse modulatory actions on set of different receptors. Using the AutoDock vina software it was shown, that PRP-1 and its homologues strongly interact with receptors, such as: mouse phosphorylated mitogen activated protein kinase 14, mouse toll like receptor 4, human Ca-sensing receptor, human epithelial growth factor receptor and human superoxide dismutase 1. As these receptors play important role in multiple cell signaling processes, the importance of their ligand peptides and homologues is obvious. But it should be stated, that, through docking experiments although are very informative, they should be considered as supplementary to real physical experiments, which should be carried out with the same receptors.
High-Throughput, 2020
D-hydantoinases catalyze an enantioselective opening of 5- and 6-membered cyclic structures and t... more D-hydantoinases catalyze an enantioselective opening of 5- and 6-membered cyclic structures and therefore can be used for the production of optically pure precursors for biomedical applications. The thermostable D-hydantoinase from Geobacillus stearothermophilus ATCC 31783 is a manganese-dependent enzyme and exhibits low activity towards bulky hydantoin derivatives. Homology modeling with a known 3D structure (PDB code: 1K1D) allowed us to identify the amino acids to be mutated at the substrate binding site and in its immediate vicinity to modulate the substrate specificity. Both single and double substituted mutants were generated by site-directed mutagenesis at appropriate sites located inside and outside of the stereochemistry gate loops (SGL) involved in the substrate binding. Substrate specificity and kinetic constant data demonstrate that the replacement of Phe159 and Trp287 with alanine leads to an increase in the enzyme activity towards D,L-5-benzyl and D,L-5-indolylmethyl h...
Pigment Cell Research, 2005
Melanins are widely used in medicine, pharmacology, cosmetics and other fields. Although several ... more Melanins are widely used in medicine, pharmacology, cosmetics and other fields. Although several technologies for the purification of water-insoluble dioxyphenylalanine (DOPA) melanins have been described, a source of water-soluble melanin is highly desirable. Here we describe an effective procedure for the isolation and purification of water-soluble melanin using the culture medium of Bacillus thuringiensis subsp. galleriae strain K1. Water-soluble melanin from this organism has an isoelectric point (pI=3.0-3.2) and was purified optimally by adsorbtion using the IA-1r resin and elution as a concentrated solution. The purified melanin obtained exhibited a similar infra-red absorbtion spectrum to synthetic melanin and contained quinolic and phenolic structures and an amino acid content of around 20% after acid hydrolysis. The molecular weight of the purified melanin determined by SDS-PAGE was 4 kDa and the electromagnetic spin resonance spectrum of the purified microbial melanin was a slightly asymmetric singlet without hyperfine structure with about 7 Gauss width of the line between points of the maximum incline and g=2.006. The concentration of paramagnetic centers in melanin is 0.21x10(18) spin/g. The results obtained provide a rapid, simple and inexpensive method for the large scale purification of water soluble melanin that may have widespread applications.
Chemico-Biological Interactions, 2008
Scientific reports, Jan 17, 2016
Activation of cell signaling by reactive chemicals and pollutants is an important issue for human... more Activation of cell signaling by reactive chemicals and pollutants is an important issue for human health. It has been shown that lipophilic nitro-benzoxadiazole (NBD) compounds rapidly move across the plasma membrane and enhance Epidermal Growth Factor Receptor (EGFR) tyrosine phosphorylation in cancer cells. Unlike ligand-dependent activation, the mechanism of this induction relies on the generation of hydrogen peroxide, which is involved in the activation of the catalytic site of the receptor and the inactivation of protein tyrosine phosphatase PTP-1B. Production of H2O2 during redox transformation of NBD compounds is associated with the transition of a monomeric form of Cu/Zn superoxide dismutase 1 (SOD1) to stable dimers. The highly stable and functionally active SOD1 dimer, in the absence of adequate activities in downstream reactions, promotes the disproportionate production and accumulation of intracellular hydrogen peroxide shortly after exposure to NBD compounds. The intrin...
In this study we present novel methodology for studying the interaction of biologically active su... more In this study we present novel methodology for studying the interaction of biologically active substances with ion channels reconstructed in bilayer lipid membranes (BLM). We utilized reconstruction of grasshopper Na+ channels in planar BLM and cyclic voltammetric technology for this purpose. BLM constructed from general lipids of bovine brain shows in NaCl as well in KCl solution a typical curve of cyclic voltammetry. In BLM reconstructed with grasshopper cephalothorax membrane proteins the capacitance and the resistance shifted to 2.2 μF/cm2 and 160 MΩ (against to 0.2 μF/cm2 and 1.3 GΩ for BLM free from membrane proteins), respectively, for BLM prepared in 1 mm diameter hole in NaCl solution, while remaining constant in KCl. The results indicate about insect sodium channels reconstruction in BLM. We used the developed methodology for determination of apparent dissociation constant (K’d) of ligand-macromolecule interaction for the model of pyrethroid insecticide and ion-channel. Th...
Using multivariate linear regression approach, open-source scripts have been developed in Gauss 4... more Using multivariate linear regression approach, open-source scripts have been developed in Gauss 4.0. for the calculation of the kinetic parameters and their dispersions for the cases of competitive, none competitive, mixed and substrate inhibitions. The methods of derivation of corresponding equations of stationary kinetics, their linearization and derivation of analytic forms of kinetic parameters and their dispersions are presented.Կիրառելով բազմաչափ գծային ռեգրեսիայի մոտեցումը` Գաուս 4.0. լեզվով հանրամատչելի ծրագրեր են մշակվել մրցակցային, անմրցակից, խառը և սուբստրատային արգելակումների դեպքերում կինետիկական պարամետրերի և դրանց դիսպերսիաների հաշվարկման համար: Ներկայացվել են ստացիոնար կինետիկայի համապատասխան հավասարումների դուրս բերման, դրանց գծայնացման և կինետիկական պարամետրերի և դրանց դիսպերսիաների հավասարումների դուրս բերման մեթոդները:Используя подход многомерной линейной регрессии, были разработаны публично доступные программы на Gauss 4.0. для расчета кинетических параметров и ...
In this study we present novel methodology for studying the interaction of biologically active su... more In this study we present novel methodology for studying the interaction of biologically active substances with ion channels reconstructed in bilayer lipid membranes (BLM). We utilized reconstruction of grasshopper Na+ channels in planar BLM and cyclic voltammetric technology for this purpose. BLM constructed from general lipids of bovine brain shows in NaCl as well in KCl solution a typical curve of cyclic voltammetry. In BLM reconstructed with grasshopper cephalothorax membrane proteins the capacitance and the resistance shifted to 2.2 μF/cm2 and 160 MΩ (against to 0.2 μF/cm2 and 1.3 GΩ for BLM free from membrane proteins), respectively, for BLM prepared in 1 mm diameter hole in NaCl solution, while remaining constant in KCl. The results indicate about insect sodium channels reconstruction in BLM.
We used the developed methodology for determination of apparent dissociation constant (K’d) of ligand-macromolecule interaction for the model of pyrethroid insecticide and ion-channel. The resistance of BLM with reconstructed ion channels was used for quantitative characterization of mentioned interaction.
Determination of K’d values for ligand – ion channel complexes, using the asymptotic method of none-linear
regression analysis, reviled 40.3±8.7 μM and 104.9±16.9 μM for known pyrethroids deltamethrin and cypermethrin,
respectively.