SUPPORT FOR THE SHAPE CONCEPT OF LIPID STRUCTURE-BASED ON A HEADGROUPVOLUME APPROACH

Headgroup volumes of seven dioleoyl lipid species, calculated from cov alent radii, are shown to correlate linearly (r = 0.95) with the abili ty of those lipids to alter the midpoint temperature of the lamellar t o inverted hexagonal phase transition (L(alpha) --> H(II)) of a 95 mol e fraction percent phosphatidylethanolamine matrix. The results illust rate the utility of the shape concept and basic considerations of head group volume as a predictive tool for the determination of lipid struc ture.