Method for obtaining structure and interactions from oriented lipid bilayers

<p>Precise calculations are made of the scattering intensity I(q) from an oriented stack of lipid bilayers using a realistic model of fluctuations. The quantities of interest include the bilayer bending modulus K<sub>c</sub>, the interbilayer interaction modulus B, and bilayer structure through the form factor F(q<sub>z</sub>). It is shown how K<sub>c</sub> and B may be obtained from data at large q<sub>z</sub> where fluctuations dominate. Good estimates of F(q<sub>z</sub>) can be made over wide ranges of q<sub>z</sub> by using I(q) in q regions away from the peaks and for q<sub>r</sub>≠0 where details of the scattering domains play little role. Rough estimates of domain sizes can also be made from smaller q<sub>z</sub> data. Results are presented for data taken on fully hydrated, oriented DOPC bilayers in the L<sub>α</sub> phase. These results illustrate the advantages of oriented samples compared to powder samples.</p>



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