The Structure of Polyunsaturated Lipid Bilayers Important for Rhodopsin Function - a Neutron Diffraction Study
Mihaela Mihailescu 1 and Klaus Gawrisch 2*
1 University of California, Irvine, CA
2 NIAAA, NIH
* To whom correspondence should be addressed. E-mail: gawrisch{at}helix.nih.gov.
Submitted on July 29, 2005
Revised on August 25, 2005
Accepted on 21 September 2005
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Abstract |
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The structure of oriented 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine bilayers with perdeuterated stearoyl- or docosahexaenoyl hydrocarbon chains was investigated by neutron diffraction. Experiments were conducted at two different relative humidities, 66% and 86%. At both humidities we observed that the polyunsaturated docosahexaenoyl chain has a preference to reside near the lipid water interface. That leaves voids in the bilayer center which are occupied by saturated stearoyl chain segments. This uneven distribution of saturated- and polyunsaturated chain densities is likely to result in membrane elastic stress which modulates function of integral receptor proteins like rhodopsin.
Key Words:
docosahexaenoic acid, membrane, neutron diffraction, phosphatidylcholine, polyunsaturation, rhodopsin
