Phospholipid bilayers, quantitative

The amount of disorder in the fatty acid side chains in a phospholipid bilayer, as a function of temperature. The side chains become much more disordered as the temperature increases through the 7m. The solid curve represents a bilayer that does not contain cholesterol the dotted curve, a bilayer with the same phospholipid plus about 25% cholesterol. The amount of random, disorderly motion of the fatty acid chains can be measured quantitatively by deuterium- or l3C-NMR. At any given temperature, the disorder is greater near the tips of the chains (toward the middle of the bilayer) than it is close to the head-groups. 

CD, Rocking Modes as Quantitative Fourier Transform Infrared Spectroscopic Probes of Conformational Disorder in Phospholipid Bilayers... 

Pure Phospholipid Bilayers. The assumptions underlying the current quantitative analyses of conformational disorder are as follows ... 

The first quantitative theory, which accounted for the repulsion between phospholipid bilayers due to a steric... 

RA. Quantitative determination of conformational disorder in the 38. acyl chains of phospholipid bilayers by infrared spectroscopy. Biochemistry 1989 28 8934-8939. 

Although phospholipid bilayers are better mimics of biomembranes than are micelles, there are few reliable quantitative data on flavonoid antioxidant activities in lipid bilayers. Terao and coworkers compared the antioxidant efficiency of quercetin and catechins (epicatechin and epicatechin gallate) with that of a-Toc in egg yolk PC liposomes using initiation by the water-soluble initiator, ABAP, and analysis of hydroperoxide formation and antioxidant consumption by HPLC. Based on the length of the induction periods and the profile of suppressed hydroperoxide formation, they concluded that quercetin and the catechins were more efficient antioxidants than a-Toc in these bilayers. Apparently the unique behavior of a-Toc in bUayers is responsible for these results (vide supra). In hexane and alcohols solution during suppressed peroxidation of methyl linoleate, the relative antioxidant activities reversed so that the flavonoids were 5-20 times less active... 

Roberts MF, Redfield AG (2004) Phospholipid bilayer surface configuration probed quantitatively by P-31 field-cycling NMR. Proc Natl Acad Sci USA 101 17066-17071... 

In many cases, the sensitivity is improved by taking advantage of the Ca labeled sites in peptides and proteins with detection. The similarities between experimental and simulated spectra demonstrate the validity of the recoupling mechanism and identify the potential for applying these experiments to virus particles or membrane proteins in phospholipid bilayers however, further development is needed in order to derive quantitative distance and angular constraints from these measurements. ... 

Wang ZJ, Desemo M (2010) A systematically coarse-grained solvent-free model for quantitative phospholipid bilayer simulation. J Phys Chem B 114(34) 11207-11220... 

In order to provide quantitative information on the elfeets of pressure on eross-peak intensities, we earned out 2D-NOESY experiments on pure POPC (l-palmitoyl-2-oleoyl-x -glyeero-3-phosphatidylcholine (Ci6 o, Cig c )) and DMPC (l,2-dimyristoyl-OT-glyeero-3-phosphatidylcholine (di-Ci4 o)) lipid bilayers.As an example, we present data on POPC, a phospholipid which is also a very important eomponent of animal cell membranes. It has an... 

Many membrane components such as phospholipid include moieties such as the C + = and 0 -P + exhibit polarisation. The membrane dipole potential ( )d has its origins in the dipole moments of polar groups from the lipidic components of the bilayer, it seems likely that the water molecules at the molecular surface of membrane also make a contribution (1). The organisation of the membrane components that contribute to this potential have been verified from neutron diffraction studies and NMR spectroscopy (23) and quite recently using cryo-EM techniques has also added quantitative estimations of the potential (24). These dipolar groups seem to be oriented in a way such that the potential located towards the hydrophobic interior of the membrane is positive with respect to the pole located towards... 

The changes in phase transition of artificial bilayers for example upon addition of drugs is only a parameter which allows an interpretation of strength and type of interaction with the studied phospholipid and is useful for the derivation of quantitative structure-interaction relationships. 

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