MEMBRANE STABILIZATION IN THE DRY STATE

We discuss current ideas of how membranes in desiccation-tolerant plan t organ(ism)s are protected from the deleterious effect of complete wa ter removal. Results of studies with model membranes showed that sugar s play a major role in preventing:fusion, phase transitions and most l ikely arse phase separations. The sugar's ability to form a stable gla ss and to interact directly with the phosphate of the phospholipid pol ar headgroup is the requirement for the protection of dry liposomes. D isaccharides alone fulfil these requirements. Dry membranes of desicca tion tolerant plants in situ often have elevated phase transition temp eratures (T-m) that are readily restored upon rehydration. Elevated T- m may point to insufficient interaction of sucrose with the polar head groups. Attempts to observe this interaction in situ by analyzing the asymmetric phosphate stretching band failed. Thus, we suggest factors other than sugars in the suppression of T-m in intact cells and provid e suggestions concerning potential roles of amphipathic compounds in t his regard. (C) 1997 Elsevier Science Inc.