Phospholipid dynamic molecular organization

The transition of a number of phospholipid chains from an ordered to a disordered state is of direct relevance to the state of the cell membrane - it is a characteristic parameter for each phospholipid. The dynamic molecular organization in vesicles and membranes has been described in detail [15] and is shown schematically in Figure 3.3. Using the thermodynamic DSC technique, changes in phase transition... 

Subczynski W K, Lewis RNAH, McElhaney RN, Hodges RS, Hyde JS, Kusumi A (1998) Molecular organization and dynamics of l-palmitoyl-2-oleoyl-phophatidylcholine bilayers containing a transmembrane a-helical peptide. Biochemistry 37(9) 3156-3164 Lewis RNAH, Liu E, Krivanek R, Rybar P, Elach CR, Mendelsohn R, Chen Y, Mant CT, Hodges RS, McElhaney RN (2007) Studies of the minimum hydrophobicity of a-helical peptides required to maintain a stable transmembrane association with phospholipid bilayer membranes. Biochemistry 46(4) 1042-1054... 

Membrane-Interaction (MI)-QSAR approach developed by Iyer et al. was used to develop predictive models of some organic compounds through BBB, and to simulate the interaction of a solute with the phospholipide-rich regions of cellular membranes surrounded by a layer of water. Molecular dynamics simulations were used to determine the explicit interaction of each test compound with the DMPC-water model (a model of dimyristoylphosphatidylcholine membrane monolayer, constructed using the software Material Studio according to the work done by van der Ploeg and Berendsen). Six MI-QSAR equations were constructed (Eqs. 74-79) ... 

Getting stractural information on the molecular supports of electropermeabilization was not easy. A key property of biological membranes is their dynamics. At a substructural level, 3IP NMR spectroscopy showed that a tilt of the orientation of the phospholipid polar head region was present in the electropermeabilized state of the membrane [45, 46]. The consequence of the interfacial water organization was proposed to be associated with a decrease of the hydration forces and the observed fusogenic state of electropermeabilized surfaces. At a more collective level, phospholipid flip-flop between the two faces of the plasma membrane was observed in the case of electropermeabilized erythrocytes [47]. 

ABSTRACT. Kinetics of proton transfer photoreactions in simple model systems is analyzed from the point of view of reaction kinetics in microphases. Protolytic photodissociation of some hydroxyaromatic compounds ArOH ( 1- and 2-na-phthol, chlorosubstituted naphthols ) was studied in micellar solutions and phospholipid vesicles by fluorescence spectra and kinetics. Experimental results give evidence of at least two localization sites of naphthols in the microphase of these systems. In lipid bilayer membranes of vesicles there are two comparable fractions of ArOH molecules, one of which undergo photodissociation, but another do not dissociate. In micelles only minor fraction ( few per cent ) of ArOH molecules do not take part in excited-state proton transfer reaction. These phenomena reflect heterogeneous structure and dynamic properties of lipid bilayer membranes and micelles. A correlation between proton transfer rate constants and equilibrium constants in microphases similar to that in homogeneous solutions is observed. Microphase approach give a possibility to discuss reactions in dynamical organized molecular systems in terms of classical chemical kinetics. 

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