Dimyristoylphosphatidylcholine lipid bilayers

It is anticipated that oligomerization as well as lattice formation is not always straightforward for a number of membrane proteins overexpressed in a host cell like E. coli, unless identiflcation and incorporation of such specific endogenous lipids to promote the formation of a 2D lattice are seriously taken into account. As a reference system to examine the NMR spectra of such proteins by site-directed NMR approach, it seems to be very important to gain an insight into how the NMR spectra of [3- C]Ala- or [l- C]Val-labeled bR incorporated into neutral lipid bilayers such as egg phosphatidylcholine (PQ, dimyristoylphosphatidylcholine (DMPC) or dipalmytoylphosphatidylcholine (DPPC) are modified by the presence or absence of a 2D crystalline lattice. 

This method was initially tested with water simulations where FM was done with reference force from ab-initio CP-MD calculations. Further this method was applied to liquid state systems by matching the force from classical all atomistic MD to CG MD. The same method was also tested for biomolecules such as dimyristoylphosphatidylcholine (DMPC) lipid bilayer and ionic liquids. 

In a vesicle an aqueous volume (water pool) is entirely enclosed by a membrane that is basically a bilayer of lipid molecules [127-137]. In the case of the unilamellar dimyristoylphosphatidylcholine (DMPC) vesicles (radius = 250 nm) there is only one such bilayer, whereas a multilamellar vesicle (radius 1000 nm) consists of several concentric bilayers. Unilamellar vesicles can be produced from multilamellar vesicles by sonication. In such a system there are two kinds of... 

Intrinsic proteins can also modify the order of phospholipid hydrocarbon chains. When cytochrome oxidase is reconstituted into vesicles of dimyristoylphosphatidylcholine, deuterated at the fatty acid methyl end, it is seen that Avq varies with the protein/ lipid ratios. Experiments performed with the lipid in the liquid-crystalline (fluid) state show (Fig. 9.24) that lipid order decreases as the protein concentration in the bilayer increases (Kang etal., 1979). This is attributed to the rough irregular protein surface in contact with the acyl chains. 

Fig. 1 Potential of mean force (relative free energy) for methane across a lipid (dimyristoylphosphatidylcholine) bilayer.The areas corresponding to the regions of the hilayer are labeled.The lower curve shows the probabiUty distribution of the atoms in the PC headgroups...

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