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High anisotropy of flow-aligned bicellar membrane systems

Maxim Kogan (Institutionen för kemi- och bioteknik, Fysikalisk kemi) ; Bengt Nordén (Institutionen för kemi- och bioteknik, Fysikalisk kemi) ; Tamas Beke-Somfai (Institutionen för kemi- och bioteknik, Fysikalisk kemi)
Chemistry and Physics of Lipids (0009-3084). Vol. 175 (2013), p. 105-115.
[Artikel, refereegranskad vetenskaplig]

In recent years, multi-lipid bicellar systems have emerged as promising membrane models. The fast orientational diffusion and magnetic alignability made these systems very attractive for NMR investigations. However, their alignment was so far achieved with a strong magnetic field, which limited their use with other methods that require macroscopic orientation. Recently, it was shown that bicelles could be aligned also by shear flow in a Couette flow cell, making it applicable to structural and biophysical studies by polarized light spectroscopy. Considering the sensitivity of this lipid system to small variations in composition and physicochemical parameters, efficient use of such a flow-cell method with coupled techniques will critically depend on the detailed understanding of how the lipid systems behave under flow conditions. In the present study we have characterized the flow alignment behavior of the commonly used dimyristoyl phosphatidylcholine/dicaproyl phosphatidylcholine (DMPC/DHPC) bicelle system, for various temperatures, lipid compositions, and lipid concentrations. We conclude that at optimal flow conditions the selected bicellar systems can produce the most efficient flow alignment out of any lipid systems used so far. The highest degree of orientation of DMPC/DHPC samples is noticed in a narrow temperature interval, at a practical temperature around 25 C, most likely in the phase transition region characterized by maximum sample viscosity. The change of macroscopic orientation factor as function of the above conditions is now described in detail. The increase in macroscopic alignment observed for bicelles will most likely allow recording of higher resolution spectra on membrane systems, which provide deeper structural insight and analysis into properties of biomolecules interacting with solution phase lipid membranes. (C) 2013 Elsevier Ireland Ltd. All rights reserved.

Nyckelord: Bicelle, Flow-orientation, Linear dichroism, Lipid membrane, Liposome, Alignment, linear dichroism spectroscopy, lipid-membranes, phospholipid bicelles, liposome membranes, polarized-light, solution nmr, orientation, mixtures, model, peptides

Denna post skapades 2014-01-09.
CPL Pubid: 192019


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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Fysikalisk kemi (2005-2014)


Biokemi och molekylärbiologi

Chalmers infrastruktur

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