Method for obtaining structure and interactions from oriented lipid bilayers - art. no. 011907

Precise calculations are made of the scattering intensity 1(q) from an orie nted stack of lipid bilayers using a realistic model of fluctuations. The q uantities of interest include the bilayer bending modulus K-c, the interbil ayer interaction modulus B, and bilayer structure through the form factor F (q(z)). It is shown how K-c and B may be obtained from data at large q(z) w here fluctuations dominate. Good estimates of F(q(z)) can be made over wide ranges of q(z) by using I(q) in q regions away from the peaks and for q(r) not equal0 where details of the scattering domains play little role. Rough estimates of domain sizes can also be made from smaller q(z) data. Results are presented for data taken on fully hydrated, oriented DOPC bilayers in t he L-alpha phase. These results illustrate the advantages of oriented sampl es compared to powder samples.