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Wyszukujesz frazę "biological membrane" wg kryterium: Wszystkie pola


Wyświetlanie 1-2 z 2
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:
Physical properties of lipid bilayer membranes: relevance to membrane biological functions.
Autorzy:
Subczynski, Witold
Wisniewska, Anna
Powiązania:
https://bibliotekanauki.pl/articles/1044298.pdf
Data publikacji:
2000
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
lipid exchange
hydrophobic barrier
oxygen transport
lipid unsaturation
membrane domains
lipid bilayer
Opis:
Over the last 25 years one of us (WKS) has been investigating physical properties of lipid bilayer membranes. In 1991 a group led by WKS was organized into the Laboratory of Structure and Dynamics of Biological Membranes, the effective member of which is AW. Using mainly the electron paramagnetic resonance (EPR) spin-labeling method, we obtained unexpected results, which are significant for the better understanding of the functioning of biological membranes. We have developed a new pulse EPR spin-labeling method for the detection of membrane domains and evaluation of lipid exchange rates. This review will be focused on our main results which can be summarized as follows: (1) Unsaturation of alkyl chains greatly reduces the ordering and rigidifying effects of cholesterol although the unsaturation alone gives only minor fluidizing effects, as observed by order and reorientational motion, and rather significant rigidifying effects, as observed by translational motion of probe molecules; (2) Fluid-phase model membranes and cell plasma membranes are not barriers to oxygen and nitric oxide transport; (3) Polar carotenoids can regulate membrane fluidity in a way similar to cholesterol; (4) Formation of effective hydrophobic barriers to the permeation of small polar molecules across membranes requires alkyl chain unsaturation and/or the presence of cholesterol; (5) Fluid-phase micro-immiscibility takes place in cis-unsaturated phosphatidylcholine-cholesterol membranes and induces the formation of cholesterol-rich domains; (6) In membranes containing high concentrations of transmembrane proteins a new lipid domain is formed, with lipids trapped within aggregates of proteins, in which the lipid dynamics is diminished to the level of gel-phase.
Źródło:
Acta Biochimica Polonica; 2000, 47, 3; 613-625
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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