2020 Impact factor 1.890
Soft Matter and Biological Physics
Eur. Phys. J. E 2, 229-245

Electron density modeling and reconstruction of infinite periodic minimal surfaces (IPMS) based phases in lipid-water systems.
II. Reconstruction of D surface based phases

P.E. Harper1 - S.M. Gruner1 - R.N.A.H. Lewis2 - R.N. McElhaney2

1 Department of Physics, Joseph Henry Laboratories, Jadwin Hall, Princeton University, Princeton NJ 08544, USA
2 Department of Biochemistry, The University of Alberta, Edmonton, Alberta, Canada T6G 2H7

Received 15 January 1999 and Received in final form 20 October 1999

This is the second of two papers dealing with the structure of lipid-water phases based on Infinite Periodic Minimal Surfaces (IPMS). The first paper describes mathematical modeling of such phases. In this paper, a new reconstruction method, called the methyl trough search, is described and used to solve the structures based on powder pattern X-ray diffraction data. Structures are derived for both a single chain lipid-water system (mono-olein) and a diacyl phospholipid-water system (2-2 methyl butyl 16:0 phosphatidylcholine). The methyl trough search uses the low electron density of the lipid methyl tails to determine the correct phasing for the electron density reconstruction. The data are consistent with a structure based on the IPMS D surface. The results are compared to other methods used to solve the mono-olein structure; the structure of the diacyl lipid has never before been solved. We discuss the subtleties involved in reconstruction of D surface based phases and the substantial artifacts that arise in low-resolution reconstructions of hydrocarbon lipids lacking heavy-atom sites.

61.30.Cz Theory and models of liquid crystal structure - 87.15.By Structure and bonding - 83.70.Jr Liquid crystals: nematic, cholesteric, smectic, discotic, etc

Copyright EDP Sciences, Società Italiana di Fisica, Springer-Verlag