1,721,039 research outputs found
Žmogaus karboanhidrazių izoformų ir jų sąveikų su slopikliais kristalografiniai tyrimai.
No full textCrystallographic studies of carbonic anhydrase isoforms and their complexes with inhibitors The goal of this study was 1) to solve the crystal structures of the complexes of several CA isoforms with a series of sulfonamide inhibitors using X-ray crystallography technique, 2) to analyze the interactions between the ligands and the CA proteins, determine the mechanisms of binding selectivity, affinity, and 3) search for the correlations between the structure and the binding thermodynamic parameters. In this work, we have published 61 crystal structures of newly synthesized sulfonamide-based CA inhibitors with 5 CA isoforms (CA I, CA II, CA IV, CA XII, and CA XIII) and also 2 mutant CA II proteins. The binding of a series of newly synthesized sulfonamides in the active sites of 5 CA isoforms was studied in detail. The mechanism of molecular recognition that increases the binding affinity to the target CA was proposed. The recognition mechanism of CA IX selective binder was studied in detail explaining the crystallographic data. The meta-cyclooctyl ring of the lead compound VD11-4-2 interacts with the hydrophobic pocket available only in the CA IX isoform and not in CA I, CA II, and CA XIII. We have described the tendencies of the changes in the binding thermodynamics between structurally similar compounds. This helps in the design of new compounds with the desired properties
Observed and intrinsic thermodynamic and kinetic parameters of sulfonamide derivative binding to carbonic anhydrases.
No full textThe aim of this work was to determine the influence of linked protonation effects to the thermodynamic and kinetic parameters of sulfonamide ligand binding to protein carbonic anhydrases (CA) and to explore the compound structure-thermodynamics and compound structure-kinetics relationships for the inhibitor binding to CA isoforms. Experiments provide information about all reactions that occur during complex formation. Protonation effect can influence the observed thermodynamic and kinetic parameters. However, dissection of protonation influence provides the intrinsic energies and association-dissociation rates of binding that do not depend on buffer or pH. To calculate the intrinsic parameters, the pKas of interacting species must be determined. Protonation constants of three CA isoforms and 25 benzenesulfonamides were determined. Thermodynamic parameters of CA-compound binding were obtained and the intrinsic parameters calculated. Analysis of the structure-thermodynamics relationship has been made. The protonation reaction also affects the kinetic parameters. SPR experiments of CA-sulfonamide binding were performed at different pHs and showed that the association rate constant depends on pH, while the dissociation rate constant does not. Interaction of compounds with CAs were obtained and the intrinsic parameters were calculated. Association rates of several compounds reached the diffusion-limitted rates. A model of intrinsic kinetic parameters was built
Crystallographic studies of carbonic anhydrase isoforms and their complexes with inhibitors.
No full textCrystallographic studies of carbonic anhydrase isoforms and their complexes with inhibitors The goal of this study was 1) to solve the crystal structures of the complexes of several CA isoforms with a series of sulfonamide inhibitors using X-ray crystallography technique, 2) to analyze the interactions between the ligands and the CA proteins, determine the mechanisms of binding selectivity, affinity, and 3) search for the correlations between the structure and the binding thermodynamic parameters. In this work, we have published 61 crystal structures of newly synthesized sulfonamide-based CA inhibitors with 5 CA isoforms (CA I, CA II, CA IV, CA XII, and CA XIII) and also 2 mutant CA II proteins. The binding of a series of newly synthesized sulfonamides in the active sites of 5 CA isoforms was studied in detail. The mechanism of molecular recognition that increases the binding affinity to the target CA was proposed. The recognition mechanism of CA IX selective binder was studied in detail explaining the crystallographic data. The meta-cyclooctyl ring of the lead compound VD11-4-2 interacts with the hydrophobic pocket available only in the CA IX isoform and not in CA I, CA II, and CA XIII. We have described the tendencies of the changes in the binding thermodynamics between structurally similar compounds. This helps in the design of new compounds with the desired properties
Thermodynamic analysis of inhibitor-carbonic anhydrase interaction and precision of binding parameters.
No full textIn this work, the binding affinities of amino-substituted and halogen-substituted benzenesulfonamides to recombinant human active carbonic anhydrases were determined. Bromine substitutions in the meta positions of compounds 13 and 14 exhibited interaction selectivity towards carbonic anhydrase VB. The intrinsic affinities of eight compounds were determined by subtracting the binding-linked protonation reactions according to the previously determined model. The addition of bromine atom in the meta position has approximately 6 kJ/mol favorable intrinsic Gibbs energy change, observed exclusively for the binding to carbonic anhydrase VB. The selectivity is significant and these lead compounds (13, 14) can be used for further development of selective inhibitors towards carbonic anhydrase VB. The precision of binding parameters was determined to evaluate the significance of data obtained by the isothermal titration calorimetry and fluorescent thermal shift assay. The results showed that the standard deviation of ΔG measured by fluorescent themal shift assay is 0.5 kJ/mol, and in the range between 0.5 and 1.6 kJ/mol depending on the intrument as measured by isothermal titration calorimetry
Thermal, morphological and mechanical properties of ethyl vanillin immobilized in polyvinyl alcohol by electrospinning process
Full text linkIn this study, polyvinyl alcohol (PVA) nanofibers with ethyl vanillin as active compound were prepared using electrospinning technique. The final products of electrospinning process were in the form of films consist of nanofibers. PVNethyl vanillin nanofibers, having fibers diameters in the range 100-1700 nm, were successfully electrospun from ethanol/water mixture of PVA and ethyl vanillin. The effects of immobilization process on ethyl vanillin thermal properties were investigated by differential scanning calorimetry (DSC). The results of DSC showed significant influence of immobilization process on thermal properties of ethyl vanillin. It was noticed that melting point of immobilized ethyl vanillin was lower (~55°C) compared to free flavor (~77°C). Our results showed that films based on PVNethyl vanillin nanofibers are mechanically stable
Žmogaus karboanhidrazių VI ir IX slopiklių efektyvumo ir toksiškumo tyrimai.
No full textThe aim of this work was to study recombinant carbonic anhydrase (CA) VI as a model of native CA VI for the determination of inhibitor intrinsic binding reactions and to explore lead inhibitors of CA IX in biological systems as an initial step of their development towards anti-cancer drugs. This thesis provides a novel concept to characterize compound efficacies by combining biochemical, biophysical, and cell biology methods. The affinities of the inhibitors were essentially identical towards the native CA VI obtained from human saliva and recombinant CA VI purified from Escherichia coli, highlighting the suitability of recombinant CA VI as a model of native CA VI for biophysical inhibitor binding studies. Analysis of the intrinsic parameters showed that the observed values can be misleading for the understanding of the chemical basis of the binding affinity. Model systems, such as zebrafish, Xenopus laevis oocytes, and human cancer cells, were used together with the enzymatic and biophysical methods to characterize newly designed CA IX inhibitors. Studies using Xenopus oocytes for the first time revealed high selectivity and efficacy (IC50 = 15 nM) of the compound against hetereologous CA IX in a biological model system. Experiments employing human cancer cells showed CA IX-dependent functional activities of tested inhibitors. Moreover, the compound reduced clonogenic cell survival in hypoxia-dependent manner using 3D cell culture
Sulfonamidinių junginių sąveikos suu karboanhidrazėmis stebimųjų bei tikrinių termodinaminių ir kinetinių parametrų nustatymas.
No full textThe aim of this work was to determine the influence of linked protonation effects to the thermodynamic and kinetic parameters of sulfonamide ligand binding to protein carbonic anhydrases (CA) and to explore the compound structure-thermodynamics and compound structure-kinetics relationships for the inhibitor binding to CA isoforms. Experiments provide information about all reactions that occur during complex formation. Protonation effect can influence the observed thermodynamic and kinetic parameters. However, dissection of protonation influence provides the intrinsic energies and association-dissociation rates of binding that do not depend on buffer or pH. To calculate the intrinsic parameters, the pKas of interacting species must be determined. Protonation constants of three CA isoforms and 25 benzenesulfonamides were determined. Thermodynamic parameters of CA-compound binding were obtained and the intrinsic parameters calculated. Analysis of the structure-thermodynamics relationship has been made. The protonation reaction also affects the kinetic parameters. SPR experiments of CA-sulfonamide binding were performed at different pHs and showed that the association rate constant depends on pH, while the dissociation rate constant does not. Interaction of compounds with CAs were obtained and the intrinsic parameters were calculated. Association rates of several compounds reached the diffusion-limitted rates. A model of intrinsic kinetic parameters was built
Bandymų, skirtų vandens skaitiklio lieto plastiko korpusui, sprendimų kūrimas.
No full textThe master thesis aims to develop quality problem solution for plastic injection moulded water meter housing. In the project, an analysis of similar plastic injection moulding process problems is done. Results of similar problem solution implementations are discussed. Based on literature research and analysis of scientific publications, the most influential moulding parameters are selected for the experiment to find the best parameter setup. The experiment is performed by producing meter housing samples using several different parameter setups. The best parameter setup is applied in the production to increase water meter housing quality. After improving quality in the plastic injection moulding process, testing of the quality increase is done using developed methods. Based on the testing results, a proposal of a new testing bench is made to reduce the quantity of outgoing faulty water meters and increase testing capabilities. Proposed quality problem solution advantages are presented. The cost of solution implementation is calculated together with meter replacement cost. Suggestions for future work are made based on this project results
Structural details of the enzymatic catalysis of carbonic anhydrase II via a mutation of valine to isoleucine /
No full textDetermination of the Volume Changes Induced by Ligand Binding to Hsp90 Using High Pressure Denaturation
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