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od 2020-09-20 |
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1. |
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Structural studies of cysteine proteases and their inhibitors Cysteine proteases (CPs) are responsible for many biochemical processes occurring in living organisms and they have been implicated in the development and progression of several diseases that involve abnormal protein turnover. The activity of CPs is regulated among others by their specific inhibitors: cystatins. The main aim of this review is to discuss the structure-activity relationships of cysteine proteases and cystatins, as well as of some synthetic inhibitors of cysteine proteases structurally based on the binding fragments of cystatins.
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Acta Biochimica Polonica, 48(1), 1-20, (2001) |
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2. |
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Molecular dynamics in supercooled m-fluoroaniline Molecular dynamics of meta-fluoroaniline (mFA) - the system which makes a simple glass forming liquid - was examined by C-13 NMR and dielectric relaxation measurements. Spin-lattice relaxation times TI, nuclear Overhauser (NOE) factors of chemically non-equivalent carbons and dielectric retaxation in mFA were measured as a function of temperature. The analysis showed that the correlation function describing molecular dynamics in mFA could he well described in terms of an asymmetric distribution of correlation rimes predicted by the Davidson-Cole model. The overall correlation times of mFA. derived from the simultaneous fitting of our TI, NOE, and dielectric data (as well as of the dielectric data obtained by Roessler's group) to the Davidson-Cole model, follow the non-Arrhenius temperature type of the behaviour in accordance with the Vogel-Fulcher equation.
(C) 2001 Elsevier Science B.V. All rights reserved. |
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Journal of Molecular Structure, 559(1-3), 179-185, (2001) |
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Commodity Science in Global Quality Perspectives. Products - Technology, Quality and Envir, 353-358, (2001) |
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(Pobrane: aktualizowanie) |
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4. |
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Molecular dynamics simulation of copolymers A series of representative molecular dynamics simulations of model Lennard-Jones copolymer chains is presented. We report measurements of thermodynamic, structural and dynamic properties of our model copolymers. For neutral copolymers we confirm our version of thermodynamic perturbation theory of the first order, while for ionic copolymers we demonstrate microphase formation and the anisotropy of the counterion diffusion.
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Task Quartely, 5(1), 17-27, (2001) |
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5. |
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Utilisation of asbestos wastes The fibrous structure of asbestos, the ubiquitous material in the environment and exhibiting
multiple applications, has proven to constitute hazards for human health. For this reason at present
utilisation of asbestos has to be stopped, its resources have to be neutralised and reutilised in a safe
way. In this paper we shall present studies on asbestos utilisation with the use of selected fluxes in
order to alter its fibrous character but preserving fire resistance of the new material.
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Physicochemical Problems of Mineral Processing, 35(1), 83-90, (2001) |
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NMR relaxation studies of polyhydroxybutyric acid (PHB) biodegradation by Escherichia Coli In the paper the biodegradation process of polyhydroxybutyric acid (PHB) copolymer, induced by Escherichia coli bacteria is monitored using nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM).
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Molecular Physics Reports, 33, 102-105, (2001) |
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7. |
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Magnetic resonance imaging of solid polymer composite In this paper the use of magic echo phase encoding (MEPSI) technique to obtain magnetic resonance image of the solid polymer composite is reported. The 2D version of MEPSI without slice selection has been adapted. The experiment shows that one can obtain an image of a solid sample whose transverse relaxation time is of the order of dozen of microseconds.
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Molecular Physics Reports, 33, 184-187, (2001) |
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8. |
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Translational diffusion in tert-butyl chloride confined to MCM-41 The translational diffusion of bulk and confined to pores of 38 Angstrom of MCM-41 tert-butyl chloride was investigated in the temperature range 293-160 K by PFGSTE experiment. The diffusivity of bulk TBC undergoes a discontinuous reduction at the melting point. The activation energy of the process was calculated to be 15.4 kJ/mol in the liquid phase and 40.6 kJ/mol in the plastic phase. Diffusivity of TBC confined to MCM-41 is described by strongly non Gaussian propagators and the echo attenuation for long diffusion times exhibit diffusion diffraction.
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Molecular Physics Reports, 33, 111-113, (2001) |
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9. |
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NMR study of restricted diffusion in lyotropic systems We present NMR diffusion measurements of n-alkyl ammonium salts-water systems (with n = 10, 12, 14) in their isotropic, lamellar and hexagonal liquid crystalline phases. Our experimental data are explained in terms of non-restricted and restricted diffusion of water molecules. Using the model of Mitra for restricted diffusion of molecules we were able to determine the Surface to Volume Ratios in lamellar phases, which were decreasing with increasing temperature.
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Molecular Physics Reports, 33, 179-183, (2001) |
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10. |
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High resolution 13C NMR and DSC studies of interdigitated- noninterdygitated phase transition in a series of alkylammonium chloridies Relation between length of the n-alkylammonium chains and phase transitions in series of alkylammonium chlorides is studied by DSC and 13C CPMAS NMR experiment. The results show that the phase transitions revealed by DSC and NMR are related with a motional freedom of CH2 and CH3 in the chains.
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Molecular Physics Reports, 33, 172-174, (2001) |
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11. |
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Fast field cycling proton NMR relaxation in decylammonium chloride/water system We have investigated the dispersion of the proton spin-lattice relaxation times in decylammonium chloride/water systems, which exhibit different liquid crystalline phases of isotropic (micelles), lamellar (layers), hexagonal (layers rolled up into cylinders), and of nematic structures. The measurements were performed in the frequency range from 3·10^3 to 1.6·10^7 Hz and in the temperature range from 10°C to 85°C. The analysis of relaxation dispersion curves gave us information on local collective molecular dynamics of the alkylammonium chains.
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Molecular Physics Reports, 33, 176-178, (2001) |
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12. |
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Structures of two highly homologous bacterial L-asparaginases: a case of enantiomorphic space groups Quasi-enantiomorphic crystals of the Y25F mutant of Escherichia coli L-asparaginase and of the native Erwinia chrysanthemi L-asparaginase were obtained in the hexagonal space groups P6(5)22 and P6(1)22, respectively. The structures of these highly homologous enzymes were solved by molecular replacement and were refined with data extending to 2.2-2.5 Angstrom. These structures were compared with each other, as well as with other L-asparaginase structures previously observed with different crystal packing. It is concluded that the observed phenomenon, which is rare, was most likely to have arisen by chance.
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Acta Crystallographica Section D-Biological Crystallography, 57, 369-377, (2001) |
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13. |
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Expression, purification and preliminary crystallographic studies of human ketohexokinase Ketohexokinase (KHK; E.C. 2.7.1.3) catalyses the (reversible) phosphorylation of fructose to fructose-1-phosphate. KHK is the first enzyme in a specialized catabolic pathway metabolizing dietary fructose to the glycolytic intermediate glyceraldehyde-3-phosphate. Mutations inactivating KHK underlie the metabolic disorder essential fructosuria. The primary structure of KHK shows no significant homology to other mammalian hexokinases. It is most similar to prokaryotic ribokinases, but catalyses a distinct phosphorylation reaction. Recombinant human KHK has been crystallized in the orthorhombic form (space group P2(1)2(1)2 or P2(1)2(1)2(1)). Single crystals of this polymorph suitable for X-ray diffraction have been obtained by vapour diffusion using 2-propanol and MPD as precipitants (pH 7.5). The crystals have unit-cell parameters a = 93.4, b = 121.5, c = 108.4 Angstrom. Diffraction data were collected to 4.3 Angstrom resolution. The asymmetric unit contains four protein molecules.
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Acta Crystallographica Section D-Biological Crystallography, 57(4), 586-588, (2001) |
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14. |
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Human cystatin C, an amyloidogenic protein, dimerizes through three-dimensional domain swapping The crystal structure of human cystatin C, a protein with amyloidogenic properties and a potent inhibitor of cysteine proteases, reveals how the protein refolds to produce very tight two-fold symmetric dimers while retaining the secondary structure of the monomeric form. The dimerization occurs through three-dimensional domain swapping, a mechanism for forming oligomeric proteins. The reconstituted monomer-like domains are similar to chicken cystatin except for one inhibitory loop that unfolds to form the 'open interface' of the dimer. The structure explains the tendency of human cystatin C to dimerize and suggests a mechanism for its aggregation in the brain arteries of elderly people with amyloid angiopathy, A more severe 'conformational disease' is associated with the L68Q mutant of human cystatin C, which causes massive amyloidosis, cerebral hemorrhage and death in young adults. The structure of the three-dimensional domain-swapped dimers shows how the L68Q mutation destabilizes the monomers and makes the partially unfolded intermediate less unstable. Higher aggregates may arise through the three-dimensional domain-swapping mechanism occurring in an open-ended fashion in which partially unfolded molecules are linked into infinite chains.
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Nature Structural Biology, 8(4), 316-320, (2001) |
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15. |
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Czwartorzędowe sole amoniowe i obszary ich zastosowania, 248-252, (2001) |
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16. |
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A novel approach to the determination of the crosslink density in rubber materials with the dipolar correlation effect in low magnetic fields We present a novel NMR approach to the determination of crosslink densities in rubber materials. The method is based on the dipolar correlation effect (DCE) on the stimulated echo examined in a series of rubber samples and linear polyisoprene. The parameter evaluated from the echo attenuation curves is the mean-squared dipolar fluctuation associated with anisotropic reorientations of macromolecular backbones. The contributions to the DCE of the constraints due to excluded volume effects and chemical crosslinks are estimated. A strong dependence of the mean-squared dipolar fluctuation on the crosslink density of rubber combined with the simplicity of performing the measurements with inexpensive low-field instruments suggests that the ME is a useful tool for routine applications. The potential and problems of performing DCE measurements in low-magnetic-field conditions are discussed in detail.
© 2001 John Wiley & Sons, Inc. |
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Journal of Polymer Science, Part B: Polymer Physics, 39(18), 2207-2216, (2001) |
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17. |
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Characterization of aged elastomers by NMR spectroscopy and microimaging In the following study we present the results of the investigation of aged elastomers by the NMR spectroscopic and microimaging methods. The series of nitrile rubber samples was investigated both filled and unfilled before and after aging. The samples were aged in a well-defined manner in the air stream at elevated temperature for several days. The T-1 and T-2 measurements and microimaging were done using the spin-echo with relaxation filters. Parameter selective images were obtained. The results show that there is a strong dependence of the relaxation times on the aging process. It is also shown that there are heterogeneous changes across the aged sample.
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Molecular Physics Reports, 33, 106-110, (2001) |
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Zaktualizowano: podstrony 2021-06-21 / bazę danych: 2024-11-02 by Webmaster: Zbigniew Fojud