I want to take phosphorous NMR of liposomes with a polymer to check its effect on the phosphate groups of the lipid. Can you tell me how to take the NMR? Most of the papers have used MAS-NMR. Is it possible to take solution state phosphorus NMR for this purpose?
liposomes are too large for solution nmr. If only solution NMR is available, bicelles (detergent/lipid mixtures which are considerably smaller than liposomes) can be detected with solution NMR. However, this will require changing the vesicle which i'm guessing you do not want
In late 70-ties P31 NMR was the technique employed by P. Cullis and B. de Kruijff and their studies resulted in the extension of Israelashvili's "molecular shape concept".
Cullis, P. R., and B. de Kuijff 1978.The polymorphic phase behaviour of phosphatidylethanolamines of natural and synthetic origin. A 31P NMR study. Biochim. Biophys. Acta.513:31-42.
I have myself used this technique in 1981 for studying the effect of amphiphiles upon the structure of biomembrane and lipid bilayer.
Kozubek A., R.A. Demel, The effect of 5-(n-alk(en)yl)resorcinols from rye on membrane structure. Biochim. Biophys. Acta 642 (1981) 242-251
Small liposomes gives the isotropic signal that is very similar to micelles, reversed micelles or SUVs.
For technical solutions I suggest reference to the articles of them.
You can get a powder pattern of MLVs in buffer. The shape of the powder pattern gives information on the phase of the phospholipids (bilayer, inverted hexagonal, etc.).
Both Jeffrey and James are correct. Generally liposomes are very difficult to look at via solution NMR due to the size and viscosity. If you have solid state NMR available it may be prudent to make use of the technique. In the following paper: Eur Biophys J (2008) 37:1031-1038 the changes in phospholipid membranes are examined after the introduction of a protein using MAS-NMR. While this may not be the answer you were looking for this may be a good paper to look at if you plan on doing any membrane protein studies using 2D crystals.
You can use multillamelar liposomes in order to observe changes in the 31P NMR spectra that reflectes changes in the phase of the phospholipids. Here an example Arch Biochem Biophys. 2006 Sep 15;453(2):224-36. Rosemary (Rosmarinus officinalis) diterpenes affect lipid polymorphism and fluidity in phospholipid membranes.
Also is possible to use the 2H NMR spectra of deuterated phospholipids in order to observe changes in the acyl chain ordering.
using solution NMR for liposomes is not practical since they are too large and heavy. solid state NMR is much more appropriate. Liposome (MLV's) preparation is very simple and you will need only a small amount of sample since the 31P nuclei found in phospholipids are 100% abundant. MAS will of course give you better resolution but even with MAS you can get significant insights into phospholipid dynamics.
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