Biophysical Journal 58: 1199-1206 (1990)
© 1990 the Biophysical Society

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Structural and dielectric properties of synthetic glycolipids in mixtures with water

Reiner Zorn ^*, Michael Grünert , Oswald Lockhoff  and Günter Nimtz 

Forschungszentrum Jülich, Institut für Festkörperforschung, D-5170 Jülich 1
II. Physikalisches Institut, Universität zu Köln, D-5000 Köln 41
Bayer AG, Geschäftsbereich Pharma, D-5600 Wuppertal, Federal Republic of Germany

ABSTRACT

Three synthetically produced glycolipids, N-(ß-D-glucopyranosyl)-N-octadecyl-stearoylamide (OSGA), N-(ß-D-glucopyranosyl-N-octadecyl-oleoylamide (OOGA), N-(ß-D-galactopyranosyl)-N-octadecyl-lauroylamide (OLGA) have been studied in different mixtures with water by x-ray diffraction and dielectric measurements with microwaves at 9.4 GHz. The measurements were performed in the temperature range -50-70°C. X-Ray diffraction revealed a direct L_ß' H_|| transition at 20°C, 60°C, and 45°C depending on the glycolipid species but nearly not on the water content. The hexagonal phases are saturated at a water content of 20 wt%. The lamellar phase absorbs even less water (< 10 wt%). The dielectric data show that in the H_|| phase the binding of water is stronger than in the L_ß' phase. In the temperature range below 0°C, OSGA and OOGA show a "subzero transition" due to the freeze-out of water in a separate ice phase. This transition can be seen in an abrupt decrease of the dielectric function because the dielectric response of ice is much smaller at microwave frequencies. OLGA does not show the subzero transition but an additional transition, hexagonal distorted hexagonal at 60°C.