The effect of salinity on the phase behaviour of purified phosphatidylethanolamine and phosphatidylglycerol isolated from a moderately halophilic eubacterium
✍ Scribed by G.C. Sutton; N.J. Russell; P.J. Quinn
- Publisher
- Elsevier Science
- Year
- 1990
- Tongue
- English
- Weight
- 947 KB
- Volume
- 56
- Category
- Article
- ISSN
- 0009-3084
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✦ Synopsis
The phase behaviour of purified phosphatidylethanolamine and phosphatidylglycerol isolated from the moderately-halophilic eubacterium Vibrio costicola grown in 1 M or 3 M NaCl-containing medium has been studied as a function of NaCI concentration using differential-scanning calorimetry, freeze-fracture electron microscopy and X-ray diffraction. The two phospholipids exhibited complex phase behaviour which was dependent on the salinity of both the bacterial culture medium and the phospholipid resuspending solution. The phosphatidylethanolamine from cultures grown in 1 M or 3 M NaCl-containing media displayed a hexagonal-ll phase and this phase persisted at temperatures up to 20 degrees lower when the lipid was dispersed in 3 M compared with 1 M NaCI. The L° phase of phosphatidylethanolamine isolated from 1 M NaCI grown cultures was favoured less when the lipid was resuspended in 3 M compared with 1 M NaCI. The Lo "-" L c phase transition temperature of the phosphatidylethanolamines coincided with ice formation. The phosphatidylglycerol samples did not exhibit non-lamellar phases over the temperature range + 50°C to -50°C. An increase in salinity of the resuspending solution increased the L ~-L~ and Lp "* L c phase transition temperatures, indicating that the L~ and L c phases were both stabilised by the higher NaCI concentration. The L° ,--L~ and Lo 4" L phase transition temperatures of phosphatidylglycerol isolated from 3 M NaCI cultures were higher than those from 1 M NaCI cultures.