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od 2020-09-20 |
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1. |
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The dispersion of water proton spin-lattice relaxation rates in aqueous human protein HC (α1 - microglobulin) solutions The H-1 NMR Fast Field Cycling relaxometry was applied to study the molecular dynamics of the human protein HC (alpha(1)-microglobulin), its hydration and aggregation in solution state. The H-1 NMRD data have revealed the complex nature of the water/protein HC system resulting from the co-existence of monomer and dimer forms of the protein in solution as well as the presence of oligosaccharides linked to the polypeptide chain. A comparison of the average correlation time values
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Protein and Peptide Letters , 16(12), 1496-1503, (2009) |
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2. |
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Synchrotron radiation small angle scattering studies of d(TTAGGG)4 oligomer in solution Telomeric DNA sequences play a crucial role in maintaining chromosome stability and integrity. In human chromosomes telomeres are composed of tandem (TTAGGG)(n) repeats. The structural parameters and low-resolution structure of a synthetic d(ITAGGG)(4) oligomer in solution has been studied in the absence and in the presence of potassium cations, with the use of the small angle scattering of synchrotron radiation. The radii of gyration R-G, calculated for d(TTAGGG)(4) oligomer (in 10 mM Tris/HCl pH 7.3) was 1.42 nm, while R-G, (in 10 mM Tris/HCl pH 7.3; 0.1 mM KCl) was 1.32 nm. The pair distance distribution function, P(r), yielded a maximum dimension of 4.55and 4.35 nm for solutions in the absence and the presence of potassium cations. On the basis of SAXS data, the low-resolution structure in solution has been reconstructed using ab inito methods.
(C) 2009 Elsevier Ltd. All rights reserved. |
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Radiation Physics and Chemistry, 78(10), S134-S136, (2009) |
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3. |
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SAXS-WAXS studies of the low-resolution structure in solution of xylose/glucose isomerase from Streptomyces Rubiginosus The structure and conformation of molecule of xylose/glucose isomerase from Streptomyces rubiginosus in solution (at pH 6 and 7.6; with and without the substrate) has been studied by small- and wide-angle scattering of synchrotron radiation (SAXS-WAXS). On the basis of the SAXS-WAXS data, the low-resolution structure in solution has been reconstructed using ab inito methods. A comparison of the models of glucose isomerase shows only small differences between the model in solution and the crystal structure.
(C) 2009 Elsevier Ltd. All rights reserved. |
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Radiation Physics and Chemistry , 78(10), 125-128, (2009) |
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4. |
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The FTIR and SAXS studies of influence of a morpholine derivatives on the DMPC-based biological membrane systems Fourier transformed infrared (FTIR) spectroscopy and small-angle scattering of synchrotron radiation have been used to analyze the influence of two zwitterionic surfactants of the sulfobetaine structure (3-(N-decylmorpholine)-1-propansulfonate and 3-(N-tetradecylmorpholine)-1-propansulfonate) on the conformational dynamics of CH2 and O-P-O groups of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and the structure of phospholipid bilayers. The presence of the surfactant causes changes in the DMPC phase transition temperature. Our small-angle X-ray scattering (SAXS) data analysis implies a gradual disappearance of the lamellar phase typical of DMPC and a probable formation of the bicellar phase or cubic phase in DMPC/surfactants system.
(C) 2009 Elsevier Ltd. All rights reserved. |
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Radiation Physics and Chemistry, 78(10), S129-S133, (2009) |
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5. |
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The effect of selected zwitterionic surfactant on the structure of hydrated DMPC Differential scanning calorimetry, Fourier transformed infrared (FTIR) spectroscopy and small angle scattering of synchrotron radiation have been used to analyse the influence of zwitterionic surfactant (3-(N-hexylmorpholine)-1-propansulfonate) on the conformational dynamics of CH(2) and CH(3) groups of 1,2-dimyrilstoyl-sn-glycero-3-phosphocholine (DMPC) and the phase behaviour of phospholipid bilayers. The surfactant causes changes in the DMPC phase transition temperature and promotes a gradual disappearance of the lamellar phase of DMPC and a probable formation of the bicellar phase.
(C) 2009 Elsevier Ltd. All rights reserved. |
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Radiation Physics and Chemistry, 78(10), S112-S115 , (2009) |
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6. |
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Crystal structure, electric field gradient, and electronic charge densities in ReB2: A single crystal X-ray, 11B nuclear magnetic resonance (NMR) and first-principles study We have grown a single crystal of ReB2 and refined its crystal structure. Our structural studies confirmed the hexagonal structure (space group P6(3)/mmc) with lattice parameters a=2.8982(1) A degrees and c=7.4723(3) A degrees. We also report the observation of first order satellites in the B-11 nuclear magnetic resonance, which indicated the presence of a nonzero quadrupole coupling frequency, nu(Q)=276 ± 3 kHz, and an asymmetry parameter eta=0 at the boron atom sites. These values are in excellent agreement with electric-field-gradient (EFG) tensor calculations based on first principles. These calculations showed that the principal axis of the most negative EFG-tensor component, V-ZZ, is parallel to the c-axis of the crystal. This behavior is in agreement with the observed excess of B p(z) charge (c direction) over the p(x) and p(y) charges and is related to stronger metal-boron bonds compared to previously studied YB12 and LaB6, where the B-B bonds are stronger. Finally, the bonding properties of ReB2 are discussed in terms of densities of states, valence-electron densities, and partial charges.
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Journal of Applied Physics, 106(3), 033514-5, (2009) |
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7. |
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Structure of an inclusive compound of bis(piperidinium-4-carboxylate)hydrogen semi-tartrate with water and methanol studied by X-ray diffraction, NMR, FTIR and DFT The complex consisting of two piperidine-4-carboxylic acid, L-tartaric acid, water and methanol molecules has been synthesized and characterized by X-ray diffraction, (1)H, (13)C NMR,(13)C CP MAS NMR, FTIR spectra and DFT calculations. The title complex is composed of the following units: piperidinium-4-carboxylate (P4C), piperidinium-4-carboxylic acid (P4CH), semi-tartrate anion (TA), water and methanol; it crystallizes in orthorhombic space group P2(1)2(1)2(1). TA anions form infinite chains through the COOH center dot center dot center dot OOC hydrogen bond of 2.503(5)angstrom. The zwitterionic P4C molecules are linked by the N(+)H center dot center dot center dot OOC hydrogen bond of 2.780(5) angstrom into chains. The P4CH cation is a bridge between the TA and P4C chains. P4CH and P4C form a homoconjugated cation through the COOH center dot center dot center dot OOC hydrogen bonds of 2.559(5) angstrom. Water interacts with TA and P4CH, while methanol interacts only with water. In the optimized molecule of the (P4C)(2)H center dot TA center dot H(2)O HOCH(3) complex, the components form a cyclic oligomer through four O-H center dot center dot center dot O and four N-H center dot center dot center dot O hydrogen bonds. The (1)H and (13)C NMR spectra elucidate the structure of the title complex in the aqueous solution. The (13)C CP MAS NMR spectrum is consistent with the X-ray results. The FTIR spectrum confirms a very complex structure of the title compound.
(C) 2009 Elsevier B.V. All rights reserved. |
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Journal of Molecular Structure, 928(1-3), 99-107, (2009) |
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8. |
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Cambridge Structural Database, (2009) |
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9. |
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Study of structure properties of organized silica sorbents synthesized on polymeric templates Mesoporous silica materials were synthesized by
applying Pluronic type polymers as pore creating agents.
The composition of a reacting mixture and the process
conditions were changed in a synthesis procedure. These
changes differentiated the characteristics of porous structure
of obtained sorbents. The parameters characterizing the pore
structure were estimated and the changes of pore arrangement
of obtained materials being a result of different synthesis
conditions were investigated. The small-angle XRD
results indicate that F cubic structure was formed what con-
firms the cage-like ordering of the synthesized silicas.
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Adsorption, 15(3) , 300-305, (2009) |
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10. |
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High-pressure small-angle neutron scattering studies of glucose isomerase conformation in solution Small-angle neutron scattering (SANS) of solutions of glucose/xylose isomerase from Streptomyces rubiginosus was measured as a function of pressure. It is shown that the structure of the enzyme in solution as seen by SANS is practically the same as that in the crystal and does not change with pressure up to 150 MPa. This reflects the unusually high structural stability of this material, which makes it extremely interesting to use as a secondary standard for pressure-dependent SANS experiments. This lack of pressure dependence of the SANS data also indicates that any possible change in hydration of the protein induced by pressure is not visible in the SANS curves. An appropriate correction procedure must be used for the SANS data in order to account for the distortion of the intensity curve due to hard-sphere and electrostatic interactions. After this correction, the isomerase can be readily used as a secondary standard for SANS measurements.
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Journal of Applied Crystallography, 42, 461-468, (2009) |
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11. |
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MRI profiles over a very wide concentration ranges: application to swelling of a bentonite clay In MRI investigation of soils, clays, and rocks, mainly mobile water is detected, similarly to that in biological and medical samples. However, the spin relaxation properties of water in these materials and/or low water concentration may make it difficult to use standard MRI approaches. Despite these limitations, one can combine MRI techniques developed for solid and liquid states and use independent information on relaxation properties of water, interacting with the material of interest, to obtain true images of both water and material content. We present procedures for obtaining such true density maps and demonstrate their use for studying the swelling of bentonite clay by water. A constant time imaging protocol provides 1D mapping of the clay distribution in regions with clay concentration above 10 vol%. T(1) relaxation time imaging is employed to monitor the clay content down to 10(-3) vol%. Data provided by those two approaches are in good agreement in the overlapping range of concentrations. Covering five orders of magnitude of clay concentration, swelling of sodium-exchanged bentonite clays from pre-compacted pellets into a gel phase is followed in detail.
(C) 2009 Elsevier Inc. All rights reserved. |
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Journal of Magnetic Resonance, 198(2), 146-150, (2009) |
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12. |
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The aluminum effect on the structure of silico-phosphate glasses studied by NMR and FTIR Silico-phosphate glasses of NaCaPO(4)-SiO(2) and NaCaPO(4)-AlPO(4)-SiO(2) system have been the subject of the presented investigations. Classes of these systems are the basis for the preparation of glassy-crystalline biomaterials [R.D. Rawlings, Clin. Mater. 14 (1993) 155]. Detailed knowledge of the precursor glass structure is necessary for proper design of the glassy-crystalline biomaterials preparation procedure. Since there is no long-range ordering in glasses, spectroscopic methods which make it possible to study the short range ordering should be applied.
MIR studies carried out in the work have allowed to establish that the glasses of the systems studied show domain composition [L.L. Hench, RJ. Splinter, T.K. Greenlee, W.C. Allen, J. Biol. Res. Symp. 2 (1971) 117: L.L. Hench, RJ. Splinter, W.C. Allen, T.K. Greenlee, J. Biol. Res. 5 (1972) 117]. Domain structure is close to that of the corresponding crystalline phases. It has been shown that even small amount of aluminium in the glass (5 mol.% of AlPO(4)) significantly influences both, its texture (microscopic and EDX studies) and its structure (spectroscopic studies). (27)Al NMR investigations have made it possible to establish unequivocally that aluminium occurs exclusively in tetrahedral coordination, i.e. it is involved in the formation of glass framework. Presence of aluminium results in significant changes in the [SiO(4)](4-) and [PO(4)](3-) tetrahedra environment which is reflected in (23)Na, (31)P and (29)Si NMR spectra. Changes in the shapes and positions of the bands in the NMR spectra of glasses belonging to the NaCaPO(4)-AlPO(4)-SiO(2) system confirm great influence of aluminium on silico-phosphate glasses structure.
(C) 2008 Elsevier B.V. All rights reserved. |
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Journal of Molecular Structure , 924-926, 107-110, (2009) |
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13. |
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Structural studies of selected DSPC-surfactant model systems of biological membranes Fourier transform infrared spectroscopy was used to analyse the influence of a cationic surfactant from the group of morpholine derivatives on the conformational dynamics of CH2 group in acyl chain of DSPC. The presence of the surfactant causes a decrease in the DSPC phase transition temperature. This result suggests that the surfactant interactions with phospholipid molecules disturb the lipid layers. The Fourier transform infrared measurements were supplemented with tests of the environmental toxicity of the surfactant used.
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Acta Physica Polonica A , 115(2), 561-564, (2009) |
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14. |
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Ring inversion in 4-hydroxy-1-methylpiperidine betaine studied by X-ray, FTIR, C-13 CP MAS NMR and DFT calculations The structure of the 4-hydroxy-1-methylpiperidine betaine has been determined by X-ray diffraction. The crystals belong to the monoclinic system, space group Pc and unit cell parameters a = 8.972(2), b = 9.747(2), c = 9.562(2) A and beta = 96.10(3)degrees. Two molecules are present in the asymmetric unit. They are in two antipodal chair conformations, in the first (A) with the methyl and hydroxyl groups in the equatorial positions and the CH2COO substituent in the axial one, and in the second (8) with the methyl and hydroxyl groups in the axial positions and the CH2COO substituent in the equatorial One. The molecules A and B form two separated zigzag chains, parallel to the z-axis. In each chain, the molecules are linked by the O-H center dot center dot center dot OOC hydrogen bonds of 2.723(3) and 2.704(3) A, in A and B, respectively. The optimized structure of the A conformer, at the B3LYP/6-31 G(d,p) approach. is by 2.09 kcal/mol more stable than B. Two resonance signals attributed to the CH3 group in C-13 CP MAS NMR spectrum confirm the conformational equilibrium in the solid-state. Two bands at 1631 and 1618 cm(-1) in the solid-state FTIR spectrum suggest the presence of two inequivalent COO groups. The calculated FTIR spectra of conformers A and B differ in the frequencies of the O-H and C-H modes.
(C) 2008 Elsevier B.V. All rights reserved. |
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Journal of Molecular Structure, 917(2-3), 76-83, (2009) |
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15. |
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Ability of lupine seeds to germinate and to tolerate desiccation as related to changes in free radicals level and antioxidants in freshly harvested seeds Seeds of yellow lupine (Lupinus Luteus L cv. Juno) were collected throughout their development on the mother plant to determine whether the ability to germinate and to tolerate desiccation is related to the level of free radicals and the changes in the redox state of ascorbate and glutathione as well as the activities of antioxidative enzymes. Electron paramagnetic resonance (EPR)-based analyses showed that development of lupine seed was accompanied by generation of free radicals with g(1) and g(2) values of 2.0049 ± 0.0004 and 2.0029 ± 0.0003, respectively. Free radical level increased significantly 25 DAF and decreased thereafter. The amount of hydrogen peroxide was high in fresh immature seeds and decreased during maturation drying. Ascorbate accumulated in lupine embryos during early seed filling stage whereas glutathione content increased during late seed filling phase. During maturation drying the redox state of both ascorbate and glutathione pools shifted towards the oxidized forms. While superoxide dismutase (SOD, EC 1.15.1.1), and ascorbate peroxidase (APX, EC 1.11.1.11) activities remained high at the early seed filling stage the activities of both dehydroascorbate reductase (DHAR, EC 1.8.5.1) and glutathione reductase (GR, EC 1.6.4.2) and that of catalase (CAT, EC 1.11.1.6) increased before seeds reached physiological maturity and decreased thereafter. The changes of isoform patterns of antioxidative enzymes were observed during seed maturation. Immature lupine seeds tested immediately after harvest acquired the ability to germinate when less than half-filled and reached high tolerance to desiccation just after physiological maturity. The physiological implications of the changes in antioxidative machinery for the acquisition of desiccation tolerance and seeds germinability are discussed.
(C) 2008 Elsevier Masson SAS. All rights reserved. |
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Plant Physiology and Biochemistry, 47(1), 56-62, (2009) |
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