Phase Transition of Biomembranes

Studies by Nuclear Magnetic Resonance

Abstract

The phase transition temperature, fatty acids and phospholipids contents were measured for phospholipid vesicles prepared from a temperature sensitive mutant of unsaturated fatty acid auxotroph of E. coli K12. The transition temperature from the gel to liquid crystal states is closely related to the content of unsaturated fatty acids in phospholipids. This mutant grows at ordinal room temperature and also can grow at higher temperatures if some amounts of KCl, sucrose or glycerol are added to the culture medium. The role of these chemicals were investigated by measuring the stability for the osmotic pressure difference between the in-and outside of liposomes. KC1 and sucrose are found to act as osmotic stabilizers but glycerol seems to play a different role.
Nmr works on biomembranes using deuterium and phosphorus magnetic resonances were reviewed.