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Wyszukujesz frazę "1H NMR" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Application of 1H and 31P NMR to topological description of a model of biological membrane fusion Topological description of a model of biological membrane fusion
Autorzy:
Janiak-Osajca, Agnieszka
Timoszyk, Anna
Powiązania:
https://bibliotekanauki.pl/articles/1039735.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
vesicle
topology
fusion
31P-NMR
1H-NMR
Opis:
The process of biological membrane fusion can be analysed by topological methods. Mathematical analysis of the fusion process of vesicles indicated two significant facts: the formation of an inner, transient structure (hexagonal phase - HII) and a translocation of some lipids within the membrane. This shift had a vector character and only occurred from the outer to the inner layer. Model membrane composed of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylserine (PS) was studied. 31P- and 1H-NMR methods were used to describe the process of fusion. 31P-NMR spectra of multilamellar vesicles (MLV) were taken at various temperatures and concentrations of Ca2+ ions (natural fusiogenic agent). A 31P-NMR spectrum with the characteristic shape of the HII phase was obtained for the molar Ca2+/PS ratio of 2.0. During the study, 1H-NMR and 31P-NMR spectra for small unilamellar vesicle (SUV), which were dependent on time (concentration of Pr3+ ions was constant), were also recorded. The presence of the paramagnetic Pr3+ ions permits observation of separate signals from the hydrophilic part of the inner and outer lipid bilayers. The obtained results suggest that in the process of fusion translocation of phospholipid molecules takes place from the outer to the inner layer of the vesicle and size of the vesicles increase. The NMR study has showed that the intermediate state of the fusion process caused by Ca2+ ions is the HII phase. The experimental results obtained are in agreement with the topological model as well.
Źródło:
Acta Biochimica Polonica; 2012, 59, 2; 219-224
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Translocation of polysialic acid across model membranes: Kinetic analysis and dynamic.
Autorzy:
Janas, Teresa
Krajiński, Henryk
Timoszyk, Anna
Janas, Tadeusz
Powiązania:
https://bibliotekanauki.pl/articles/1044181.pdf
Data publikacji:
2001
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
polysialic acid
1H-NMR
electrical equivalent circuit
polycation flux
polyanion flux
lipid bilayers
membrane transport
Opis:
Transmembrane translocation of polyion homopolymers takes place in the case of polyanionic polysialic acid (polySia), polyanionic polynucleotides and polycationic polypeptides. The purpose of this work was to determine the role of membrane electrical parameters on the kinetics of polyion translocation, the influence of polysialic acid on ion adsorption on positively charged membrane surface and the dynamics of the phospholipid hydrocarbon chains and choline group by using 1H-NMR. The analysis of polyion translocation was performed by using the electrical equivalent circuit of the membrane for the initial membrane potential equal to zero. The changes in polysialic acid flux was up to 75% after 1 ms in comparison with the zero-time flux. Both a decrease of membrane conductance and an increase of polyion chain length resulted in the diminution of this effect. An increase of praseodymium ions adsorption to positively charged liposomes and an increase of the rate of segmental movement of the -CH2 and -CH3 groups, and the choline headgrup of lipid molecules, was observed in the presence of polySia. The results show that the direction of the vectorial polyion translocation depends both on the membrane electrical properties and the degree of polymerization of the polymer, and that polysialic acid can modulate the degree of ion adsorption and the dynamics of membrane lipids.
Źródło:
Acta Biochimica Polonica; 2001, 48, 1; 163-173
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preparation and Characterization of a Novel Hyperbranched Polyester Polymers Using A2+B3 Monomers
Autorzy:
Al-Mutairi, Nabeel Hasan
Al-Zubiedy, Ali
Al-Zuhairi, Ali J
Powiązania:
https://bibliotekanauki.pl/articles/26081324.pdf
Data publikacji:
2023
Wydawca:
Stowarzyszenie Menedżerów Jakości i Produkcji
Tematy:
hiperrozgałęziony poliester HBP
monomer A2+B3
polycondensation
1H-NMR
GPC
hyperbranched polyester HBP
A2+B3 monomer
Opis:
Compared to linear analogs, hyperbranched polymers (HBPs) have gotten much attention in the last decade because of their intrinsic globular topologies and distinctive features like low viscosity, high solubility, and a high degree of functionality. In this work, four types of hyperbranched polyester polymer HBPs have been synthesized using the A2+B3 polycondensation methodology. Firstly, the starting material B3 monomer (Pyrimidine-2,4,6-triol) has been synthesized using urea and malonic acid with the presence of sodium Na as the catalyst for the reaction. Secondly, four types of materials (tartaric acid TA, adipic acid AD, maleic acid MA, and phthalic anhydride PA) as A2 monomers were added to the starting material B3 monomer in an oil bath to prepare the four types of HBP. The chemical structure of HBPs was characterized by FTIR, and 1H-NMR. The molecular weight of the prepared HBPs was characterized by gel permeation chromatography GPC, and thermal properties were characterized by differential scanning calorimetry DSC and thermal gravimetric analysis TGA. FTIR results showed that there are new bands, such as C-O-C between A2 and B3 monomers, as indicated by 1H-NMR. In addition, GPC shows that the prepared polymers have a narrow molecular weight distribution with good thermal stability, as indicated by DSC and TGA.
Źródło:
Production Engineering Archives; 2023, 29, 1; 28--36
2353-5156
2353-7779
Pojawia się w:
Production Engineering Archives
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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