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    Wyświetlanie 1-14 z 14
    Tytuł:
    Exceptional molecular organization of canthaxanthin in lipid membranes
    Autorzy:
    Sujak, Agnieszka
    Powiązania:
    https://bibliotekanauki.pl/articles/1039765.pdf
    Data publikacji:
    2012
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    molecular interactions
    retinopathy
    lipid membranes
    canthaxanthin
    Opis:
    Canthaxanthin (β,β-carotene 4,4' dione) used widely as a drug or as a food and cosmetic colorant may have some undesirable effects on human health, caused mainly by the formation of crystals in the macula lutea membranes of the retina of an eye. Experiments show the exceptional molecular organization of canthaxanthin and a strong effect of this pigment on the physical properties of lipid membranes. The most striking difference between canthaxanthin and other macular pigments is that the effects of canthaxanthin at a molecular level are observed at much lower concentration of this pigment with respect to lipid (as low as 0.05 mol%). An analysis of the molecular interactions of canthaxanthin showed molecular mechanisms such as: strong van der Waals interactions between the canthaxanthin molecule and the acyl chains of lipids, restrictions to the segmental molecular motion of lipid molecules, modifications of the surface of the lipid membranes, effect on the membrane thermotropic properties and finally interactions based on the formation of the hydrogen bonds. Such interactions can lead to a destabilization of the membrane and loss of membrane compactness. In the case of the retinal vasculature, it can lead to an increase in the permeability of the retinal capillary walls and the development of retinopathy.
    Źródło:
    Acta Biochimica Polonica; 2012, 59, 1; 31-33
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Inter - and inframolecular dynamics of iron porphyrins
    Autorzy:
    Dziedzic-Kocurek, K.
    Okła, D.
    Stanek, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/147410.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    EXAFS
    Fe-porphyrins
    molecular interactions
    Mössbauer spectroscopy
    Opis:
    The temperature dependent Mössbauer spectroscopy and EXAFS analysis of the dynamical properties of selected iron-porphyrin derivatives: FeTPPCl and FePPIXCl has been presented. It has been shown that these iron-porphyrin properties may be modified by the outer ligands, but they are also strongly influenced by the intermolecular interactions, which are reduced in frozen solutions of the studied complexes.
    Źródło:
    Nukleonika; 2013, 58, 1; 7-11
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Molecular Interactions in Binary Organic Liquid Mixtures Containing Ethyl Oleate and Ethanol at 2MHz Frequency
    Autorzy:
    Manukonda, S.
    Kumar, G. P.
    Babu, C. P.
    Powiązania:
    https://bibliotekanauki.pl/articles/412193.pdf
    Data publikacji:
    2015
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Ethyl Oleate
    Ethanol
    molecular interactions
    adiabatic compressibility
    Opis:
    Molecular interactions of binary mixtures of Ethanol with a new organic compound Ethyl Oleate are investigated at a constant ultrasonic frequency of 2MHz under the temperature range of 303.15K-318.15K. The effect of mole fraction of Ethyl Oleate on velocity of sound wave and the density and viscosity of binary mixtures at various temperatures were studied. The effects on density (ρ), viscosity (η), adiabatic compressibility (βad), inter molecular free length (Lf) and internal pressure (Пi) also was studied.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2015, 40; 17-23
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Theoretical evaluation of ultrasonic velocities of binary liquid mixtures of 1-bromopropane in chlorobenzene at 303.15, 308.15, 313.15 and 318.15 K
    Autorzy:
    Babu, Ch. P.
    Kumar, G. P.
    Nagarjun, B.
    Samatha, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/412079.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    ultrasonic velocities
    molecular interactions
    1-bromopropane and chlorobenzene
    Opis:
    Theoretical velocities of binary liquid mixtures of 1-bromopropane with chlorobenzene at 2 MHz and four different temperatures 303.15, 308.15, 313.15 and 318.15 K, have been evaluated as a function of concentration and temperature. The experimental values are compared with theoretical models of liquid mixtures such as Nomoto, Van Dael-Vangeel, Impedance Relation, Rao’s Specific Velocity Method, Junjie’s relations and Free Length Theory. In the chosen system there is a good agreement between experimental and theoretical values calculated by Nomoto’s theory. The deviation in the variation of U2exp/ U2imx from unity has also been evaluated for explaining the non ideality in the mixtures. The results are explained in terms of intermolecular interactions occurring in these binary liquid mixtures.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 11, 1; 9-17
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Acoustical studies of binary liquid mixtures of p-chlorotoluene in benzene at different temperatures
    Autorzy:
    Kumar, G. P.
    Babu, Ch. P.
    Samatha, K
    Jyosthna, A. N.
    Showrilu, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/412275.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    ultrasonic velocity
    thermodynamic parameters
    p-chlorotoluene
    molecular interactions
    Opis:
    Ultrasonic velocities (U), densities (ρ), and coefficient of viscosities (η) are measured for binary mixtures containing (i) p-chlorotoluene and (ii) benzene at 303.15 K, 308.15 K, 313.15 K and 318.15 K to understand the molecular interaction. Various acoustical parameters such as adiabatic compressibility (βad), free length (Lf), acoustic impedance (Z), free volume (Vf), molar volume (Vm), Rao’s constant (R), Wada’s constant (W) and internal pressure (πi), are calculated from the measured values of U, ρ, and η. The trend in acoustical parameters also substantiates to asses strong molecular interactions.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 10; 25-37
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Acoustical studies of some synthesized Schiff base derivatives in dimethylsulphoxide at 303.15 K, by ultrasonic velocity measurement
    Autorzy:
    Gopi, C.
    Santhi, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/412151.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    density
    viscosity
    ultrasonic velocity
    DMSO
    acoustical parameters
    molecular interactions
    Opis:
    The density, viscosity and sound velocity of five Schiff bases (1-5) derivatives in DMSO solutions have been studied at 303.15 K over a wide range of concentration. From these experimental data, some acoustical parameters such as Molar volume (Vm), Specific Acoustic Impedance (Z), Adiabatic compressibility (βad), Intermolecular Free Length (Lf), Rao’s Constant (R), Molar compressibility (W), Relaxation time(τ), van der Waals constant (b), Relaxation strength (r), Relative association (RA), Isothermal compressibility (βT ) , Isothermal expansion co-efficient (α) ,Free volume (Vf) and Internal pressure (πi) and Ultrasonic attenuation (α/f²) have been evaluated. A fairly good correlation between a given parameter and concentration is observed. The results are interpreted in terms of molecular interactions like solvent-solvent, solvent-solute and solute-solute interactions.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 17, 1; 50-66
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of temperature on thermo-physical properties of pyrazolo quinazoline derivatives by ultrasonic studies
    Autorzy:
    Baluja, Shipra
    Ramavat, Paras
    Nandha, Kajal
    Powiązania:
    https://bibliotekanauki.pl/articles/1192659.pdf
    Data publikacji:
    2016
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    pyrazolo quinazoline derivatives
    Acoustical parameter
    Molecular interactions
    Density
    apparent molar compressibility
    Opis:
    Density (ρ), Sound velocity (U) and viscosity (ɳ) of pure solvent N,N-dimethylformamide (DMF) and solutions of pyrazolo quinazoline derivatives in DMF were taken at different concentration range and at different temperatures by using Antone paar. From these experimental data, some acoustical parameters such as adiabatic compressibility (κs), intermolecular free length (Lf), solvation number (Sn), apparent molar compressibility (fk), apparent molar volume (fv), internal pressure (π) etc., have been determined and correlated with the concentration (C).With concentration and temperatures, Linear or non-linear increases or decreases of acoustical parameters shows the existence of strong molecular interactions between solute and solvent. The results are interpreted in terms of solute-solute and solute-solvent interactions to understand the behavior of synthesized compounds in solutions.
    Źródło:
    World Scientific News; 2016, 47, 2; 89-111
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Elektrooptyczny efekt Kerra w chemii
    Electrooptic Kerr effect in chemistry
    Autorzy:
    Prezhdo, O.
    Olan, K.
    Zubkowa, W.
    Preżdo, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/171825.pdf
    Data publikacji:
    2011
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    elektrooptyczny efekt Kerra
    analiza konformacyjna
    wewnątrzcząsteczkowe oddziaływania
    oddziaływania wewnątrzcząsteczkowe
    oddziaływania międzycząsteczkowe
    polaryzowalność
    moment dipolowy
    stała Kerra
    electro-optical Kerr effect
    conformational analysis
    intra-molecular interactions
    intermolecular interactions
    polarizability
    dipole moment
    Kerr constant
    Opis:
    The electro-optical Kerr effect finds wide application in conformational analysis of molecules and molecular aggregates [1–5], particularly in cases where the standard X-ray and NMR techniques cannot be used. For instance, NMR allows to establish conformations of linear and cyclic unsaturated organic compounds. However, it is less effective in an analysis of molecular complexes, particularly of those that have several rotational symmetry axes. In such cases a combination of techniques based on molecular dipole moments, electro-optical Kerr effect, optical Kerr effect, IR spectroscopy, and Rayleigh scattering can be applied [6]. The foundations of conformational analysis of molecular complexes using several complementary physical approaches are developed in Ref. [7]. The electro-optical methods are particularly useful for an investigation of intramolecular interactions [8–18]. The strength, direction and other details of intramolecular interactions can be determined by analyzing the deviations of the experimental molar Kerr constant (mK) from its value calculated according to the tensor-additive scheme that operates with polarizability tensors of molecular cores and functional groups [19, 20]. For instance, using this approach it has been shown that weakening of conjugation in an electron donor-acceptor chain can lead to flattening of the molecular structure [21]. The Kerr constant is also very sensitive to intermolecular interactions [22–29]. In order to assess quantitatively an extent of the solvent effect on the mK values, both molecular and continuum models of solution structure have been used [30, 31]. The mK values are greatly affected by the mutual orientation of solvent and solute molecules, which interact by dispersive, inductive and dipole-dipole forces [32]. Hydrogen and donor-acceptor bonding have an even stronger influence on the mK values [33]. The equimolar mixtures approach developed in Ref. [34] allows to determine the molar Kerr constant (mK), dipole moment (m), equilibrium constant (K) and, ultimately, structure of a molecular complex based on measurements of the Kerr constant (B), dielectric permittivity (e), density (d) and refractive index (n) of a series of dilute solutions of the complex. Future trends in the development of the electro-optical methods in chemistry are discussed. Theories that relate the electric-optic proprieties of molecules with their reactivity are particularly important. Such theories should be able to predict the changes in the polarizabilities and dipole moments of bonds, molecules and molecular aggregates during the course of chemical reactions.
    Źródło:
    Wiadomości Chemiczne; 2011, 65, 1-2; 1-31
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modelling drug-receptor interactions in an average binding site for NK2
    Autorzy:
    Alagona, G.
    Ghio, C.
    Monti, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1953954.pdf
    Data publikacji:
    1998
    Wydawca:
    Politechnika Gdańska
    Tematy:
    receptor modelling
    docking
    non covalent interactions
    molecular mechanics
    molecular dynamics
    substituent effects
    Opis:
    A tentative procedure applied to the search for a new antagonist of neurokinin A (NKA) is presented. In parallel a tentative 3-D model of the NK2 receptor was created, using bacteriorhodopsin (BRD) as a template. The residue substitutions were performed in BRD to obtain the sequence for NK2R_H and the seven a-helical segments were optimized forcing the a-helical backbone to match the corresponding aligned parts of BRD, while the arrangements of the side chains were model built based on available site-directed mutagenesis studies. Constrained MM and molecular dynamics simulations were carried out H-bonding a low energy conformer of the known drugs to residues in the receptor site, allowing both the receptor site and drugs to relax. The Connolly surface for each ligand allowed to determine an "average" binding site in which all the low energy conformers of known and prospective drugs were docked and classified according to a statistical index. The whole procedure was repeated exploiting the lately published structure of an actual G protein coupled receptor as a better template, thus producing a cavity in the binding site to directly dock the drugs. Corollary validations of the force fields used are also mentioned. In addition intra- and intermolecular interactions suitable to produce more active drugs were evaluated.
    Źródło:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 1998, 2, 4; 563-581
    1428-6394
    Pojawia się w:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Polymer Reinforced DNAN/RDX Energetic Composites: Interfacial Interactions and Mechanical Properties
    Autorzy:
    Qian, W.
    Chen, X.
    Luo, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/358170.pdf
    Data publikacji:
    2017
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    energetic composites
    dinitroanisole
    molecular dynamics
    interfacial interactions
    mechanical properties
    Opis:
    2,4-Dinitroanisole (DNAN) has excellent properties as a replacement for 1,3,5-trinitrotoluene (TNT) in melt-cast explosives, and the polymeric modifier used is critical to the mechanical modification of the DNAN/RDX energetic composite. In our research, the typical polymeric modifier acrolein-pentaerythritol resin (APER) was successfully added experimentally to the DNAN/RDX system, and the effects of interfacial interactions on the mechanical properties of these polymers in reinforcing the DNAN/RDX energetic composites were investigated by molecular dynamics simulations, scanning electron microscopy (SEM) and mechanical testing. The results showed that strong attractive interactions exist between the polymer and the explosives, wherein van der Waals forces were found to play the main role. The morphological micro-images also showed tight binding between the polymer/explosive interfaces, which supported the calculated strong interfacial interactions. The mechanical tests confirmed that adding the polymers can obviously reinforce the mechanical strength and toughness of DNAN/RDX systems. The above observations revealed that the cooperative effects of the APER polymer can help to reinforce the interfacial interactions and mechanical properties of DNAN/RDX composites, which is of importance in the formulation and mechanical evaluation of advanced energetic composites.
    Źródło:
    Central European Journal of Energetic Materials; 2017, 14, 3; 726-741
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Molecular Dynamics Simulation Studies of the CL-20/DNB Co-crystal
    Autorzy:
    Sun, T.
    Xiao, J. J.
    Ji, G. F.
    Zhao, F.
    Xiao, H. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/358075.pdf
    Data publikacji:
    2016
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    CL-20/DNB co-crystal
    composite
    interactions
    mechanical properties
    molecular dynamics simulation
    Opis:
    Molecular dynamics (MD) simulation was conducted for a DNB (1,3-dinitrobenzene) crystal, a ε-CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane) crystal, a CL-20/DNB co-crystal and a CL-20/DNB composite. From the calculated maximum bond length (Lmax) of the N−NO2 trigger bond, the cohesive energy density (CED) and the binding energy (Ebind), it was found that the CL-20/DNB co-crystal is more insensitive than its composite. Its thermal stability is also better than that of its composite. The pair correlation function (PCF) analysis method was applied to investigate the interfaces between different molecular layers in the CL-20/DNB co-crystal, and in the composite. Additionally, the calculated mechanical data showed that the moduli of the CL-20/DNB co-crystal and its composite are smaller and their elastic elongation and ductility are better than those of the ε-CL-20 and DNB crystals.
    Źródło:
    Central European Journal of Energetic Materials; 2016, 13, 3; 677-693
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fluctuations of kinetic energy at molecular dynamics and the atomic interactions in crystals
    Autorzy:
    Andriyevsky, B.
    Piekarski, J.
    Andriyevska, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/118444.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Koszalińska. Wydawnictwo Uczelniane
    Tematy:
    interatomic interactions
    molecular dynamics
    silicon
    phonon relaxation time
    oddziaływania międzyatomowe
    dynamika molekularna
    krzem
    czas relaksacji fononów
    Opis:
    The calculation method of the molecular dynamics has been applied to study the correlation of the kinetic energy fluctuations and the relaxation time of the velocity autocorrelation function and the phonon relaxation time in a crystal. On the basis of the molecular dynamics data for silicon crystal obtained at different temperatures in the range 200 K – 1000 K the correlation between the kinetic energy fluctuations and the relaxation time of the velocity autocorrelation function has been calculated with the relatively high coefficient of determination R2 = 0.9396. The correlation obtained and the corresponding approach substantiate a use of the kinetic energy fluctuations for the calculation of values related to the heat conductivity in the silicon based semiconductors (coefficients of thermal conductivity and diffusivity).
    Obliczeniowa metoda dynamiki molekularnej została zastosowana do badania korelacji fluktuacji energii kinetycznej i czasu relaksacji autokorelacyjnej funkcji prędkości i czasu relaksacji fononów w krysztale. Na bazie danych dynamiki molekularnej kryształu krzemu otrzymanych w różnych temperaturach w zakresie 200 K – 1000 K została obliczona korelacja fluktuacji energii kinetycznej i czasu relaksacji autokorelacyjnej funkcji prędkości, która cechuje się stosunkowo wysokim współczynnikiem determinacji R2 = 0.9396. Otrzymana korelacja uzasadnia zastosowanie fluktuacji energii kinetycznej do badań obliczeniowych wielkości powiązanych z przewodnością cieplną półprzewodników na bazie krzemu (współczynniki przewodności i dyfuzyjności cieplnej).
    Źródło:
    Zeszyty Naukowe Wydziału Elektroniki i Informatyki Politechniki Koszalińskiej; 2018, 12; 19-24
    1897-7421
    Pojawia się w:
    Zeszyty Naukowe Wydziału Elektroniki i Informatyki Politechniki Koszalińskiej
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The two faces of the proteins structure - Application of knowledge about intrinsically disordered proteins in rational drug design
    Dwie twarze struktury przestrzennej białek – zastosowanie wiedzy o białkach samoistnie nieuporządkowanych w racjonalnym projektowaniu leków
    Autorzy:
    Górka, Adam
    Bonarek, Piotr
    Powiązania:
    https://bibliotekanauki.pl/articles/41204476.pdf
    Data publikacji:
    2013
    Wydawca:
    Uniwersytet Kazimierza Wielkiego w Bydgoszczy
    Tematy:
    elementy rozpoznawania molekularnego
    oddziaływania białko białko
    fałdowanie białek
    cechy sekwencji aminokwasowej białek
    molecular recognition features
    protein protein interactions
    protein folding
    amino acid sequence properties of proteins
    Opis:
    Proteins are an essential component of living cells. Proper understanding of the properties of their structure is crucial to understanding their function in nature. The proteins and their fragments may exist in four states of structure organization: ordered, molten globule, pre molten globule and random coil. The particular function of proteins depend on any one of these states or a transition between them. A significant proportion of proteins in nature is composed of a mixture of ordered and intrinsically disordered regions, that fulfil important roles in the processes like signal transduction, cell cycle regulation and many others. The standard approach for rational drug design does not work for intrinsically disordered proteins (IDPs) and requires modified strategies. Furthermore, the majority of proteins with long intrinsically disordered regions (IDRs) use short molecular recognition elements (MoRFs), which undergo transition from disorder to order state and adopt various structures in numerous protein protein interactions. These interactions are an attractive therapeutic target for the pharmaceutical industry in the process of rational drug design.
    Białka są podstawowymi składnikami żywych komórek. Prawidłowe rozumienie cech ich struktury przestrzennej jest kluczowe dla zrozumienia ich funkcjonowania w organizmach żywych. Białka mogą przebywać w czterech wyróżnionych stanach organizacji struktury przestrzennej: uporządkowanym, stopionej globuli, pre-stopionej globuli i kłębka statystycznego. Funkcje białek mogą być związane z każdym tych stanów, a co ważniejsze, z przejściami pomiędzy tymi stanami. Znacząca liczba białek w przyrodzie zbudowana jest z mieszaniny rejonów uporządkowanych oraz samoistnie nieuporządkowanych, które pełnią ważne role w procesach przekazu sygnału, regulacji cyklu komórkowego i wielu innych. Standardowe podejście do racjonalnego projektowania leków nie sprawdza się w przypadku białek samoistnie nieuporządkowanych (IDPs) i wymaga zmodyfikowanej strategii postępowania. Jednym z atrakcyjnych celów terapeutycznych dla przemysłu farmaceutycznego są krótkie fragmenty łańcucha aminokwasowego pełniące funkcje elementów rozpoznawania molekularnego (MoRFs), które porządkują swoją strukturę w różnorodnych i licznych oddziaływaniach z innymi białkami. Charakterystyczną cechą MoRFs-ów jest ich częste występowanie w rejonach samoistnie nieuporządkowanych łańcucha polipeptydowego.
    Źródło:
    Studia i Materiały Informatyki Stosowanej; 2013, 10; 7-12
    1689-6300
    Pojawia się w:
    Studia i Materiały Informatyki Stosowanej
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Badanie struktury i dynamiki N-terminalnych sekwencji dermorfiny i ich analogów z wykorzystaniem spektroskopii NMR w ciele stałym i rentgenografii
    Studies on the structure and dynamics of N-terminal sequences of dermorphin and their analogs by means of solid state NMR spectroscopy and XRD
    Autorzy:
    Trzeciak-Karlikowska, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/171648.pdf
    Data publikacji:
    2012
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    peptydy opioidowe
    oddziaływania CH-pi
    dynamika molekularna
    oddziaływanie peptyd–fosfolipid
    spektroskopia NMR
    1H Ultra Fast MAS NMR
    PISEMA MAS
    PILGRIM
    XRD
    opioid peptides
    CH-pi interactions
    molecular dynamics
    peptide–phospholipid interaction
    NMR spectroscopy
    Opis:
    Deltorphin I (Tyr-d-Ala-Phe-Asp-Val-Val-Gly-NH_2) and dermorphin (Tyr-d-Ala-Phe- -Gly-Tyr-Pro-Ser-NH_2) are natural opioid peptides that have been isolated from the skin of South American frogs [1]. The presence of d-amino acid is crucial for their biological activity. The synthetic analogs of given heptapeptides containing l-alanine are not analgesics [2]. Analysis of the influence of stereochemistry on molecular packing, dynamics and biological functions of neuropeptides is still important for receptor studies and practical applications (e.g. design of new selective pain killers). Presented research is focused on the structure and dynamics of two N-terminal sequences of dermorphin: tripeptide Tyr-d-Ala-Phe 1, tetrapeptide Tyr-D-Ala-Phe-Gly 2, and their analogs with l-alanine: Tyr-Ala-Phe 3 and Tyr-Ala-Phe-Gly 4, using solid state NMR and X-ray diffraction. This study clearly demonstrates that 1 and 2 crystallized under different conditions to form exclusively one structure [3, 4]. In contrast, tripeptide and tetrapeptide with l-Ala in the sequence very easily form different crystal modifications. Tyr-Ala-Phe 3 crystallizes into two forms: 3a and 3b [5], while Tyr-Ala-Phe-Gly 4 gives three modifications: 4a, 4b and 4c [4]. It seems that one of the factors, which can be important in the preorganization mechanism anticipating the formation of crystals, is the intramolecular CH-đ interaction between aromatic rings of tyrosine and/or phenylalanine and the methyl group of alanine. Such interaction is possible only for d-Ala residue. For l-Ala in the peptide sequence, the methyl group is aligned on the opposite side with respect at least to one of the aromatic groups. It can be further speculated that such internal CH-π contacts can also occur during the interaction of ligand–receptor, making the message sequence of opioid peptides more rigid and finally selective. By employing different NMR experiments (e.g. PISEMA MAS and PILGRIM) it was proven that the main skeleton of analyzed peptides is rigid, whereas significant differences in the molecular motion of the aromatic residues were observed [4, 6]. Solid state 2H NMR spectroscopy of samples with deuterium labeled aromatic rings: Tyrd4-d-Ala-Phe 5, Tyr-d-Ala-Phed5 6, Tyrd4-Ala-Phe 7, Tyr-Ala-Phe^d5 8 was used to analyze the geometry and time scale of the molecular motion. At ambient temperature, the tyrosine ring of sample 5 is rigid and in the sample 6 the phenylalanine ring undergoes a "π -flip". The tyrosine rings of form I of 7 and 8 are static, while the phenylalanine rings of form II of 7 and 8 undergo a fast regime exchange [6]. Variable temperature 2H measurements proved that the tyrosine and phenylalanine rings of two forms of compounds 7 and 8 became more mobile with increasing temperature. In contrast, the aromatic rings of samples 5 and 6 preserve their dynamics regime (static tyrosine and "π -flip" phenylalanine) in a large range of temperatures [6]. The analysis of 13C, 15N labeled tetrapeptide Tyr-D-Ala-Phe-Gly 2’-phospholipid membrane interactions suggests that peptide 2’ is aligned on the surface of the membrane (RFDR MAS) and the sandwich-like π -CH_3-π arrangement of the pharmacophore is preserved (DARR) [7].
    Źródło:
    Wiadomości Chemiczne; 2012, 66, 9-10; 867-891
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-14 z 14

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