INTERACTIONS BETWEEN SOLUBLE SUGARS AND POPC (1-PALMITOYL-2-OLEOYLPHOSPHATIDYLCHOLINE) DURING DEHYDRATION - VITRIFICATION OF SUGARS ALTERS THE PHASE-BEHAVIOR OF THE PHOSPHOLIPID
Kl. Koster et al., INTERACTIONS BETWEEN SOLUBLE SUGARS AND POPC (1-PALMITOYL-2-OLEOYLPHOSPHATIDYLCHOLINE) DURING DEHYDRATION - VITRIFICATION OF SUGARS ALTERS THE PHASE-BEHAVIOR OF THE PHOSPHOLIPID, Biochimica et biophysica acta. Biomembranes, 1193(1), 1994, pp. 143-150
The phase behavior of 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) w
as characterized as a function of hydration in the presence of combina
tions of sugars representative of sugars found in seed embryos having
differing degrees of desiccation tolerance. The tendency of the sugar
mixes to vitrify was also monitored as a function of hydration. Using
differential scanning calorimetry, it was found that all sugars dimini
shed the increase in the gel-to-fluid phase transition temperature (T-
m) of POPC that occurred upon dehydration of the pure lipid. These res
ults are analyzed in terms of the osmotic and volumetric properties of
sugars. Also, it was found that in those samples for which the glass
transition temperature (T-g) was greater than the T-m of POPC, T-m was
lowered by approx. 20 C degrees from the value for the fully hydrated
lipid. X-ray diffraction data confirmed that acyl chain freezing was
deferred to a lower temperature during cooling of vitrified samples. T
he significance of these results is discussed in terms of the ability
of many organisms to tolerate desiccation.