Abstract
A method that enables temperature-composition phase diagram construction at unprecedented rates is described and evaluated. The method involves establishing a known temperature gradient along the length of a metal rod. Samples of different compositions contained in long, thin-walled capillaries are positioned lengthwise on the rod and "equilibrated" such that the temperature gradient is communicated into the sample. The sample is then moved through a focused, monochromatic synchroton-derived x-ray beam and the image-intensified diffraction pattern from the sample is recorded on videotape continuously in live-time as a function of position and, thus, temperature. The temperature at which the diffraction pattern changes corresponds to a phase boundary, and the phase(s) existing (coexisting) on either side of the boundary can be identified on the basis of the diffraction pattern. Repeating the measurement on samples covering the entire composition range completes the phase diagram. These additional samples can be conveniently placed at different locations around the perimeter of the cylindrical rod and rotated into position for diffraction measurement. Temperature-composition phase diagrams for the fully hydrated binary mixtures, dimyristoylphosphatidylcholine (DMPC)/dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylethanolamine (DPPE)/DPPC, have been constructed using the new temperature gradient method. They agree well with and extend the results obtained by other techniques. In the DPPE/DPPC system structural parameters as a function of temperature in the various phases including the subgel phase are reported. The potential limitations of this steady-state method are discussed.
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Selected References
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- Alecio M. R., Golan D. E., Veatch W. R., Rando R. R. Use of a fluorescent cholesterol derivative to measure lateral mobility of cholesterol in membranes. Proc Natl Acad Sci U S A. 1982 Sep;79(17):5171–5174. doi: 10.1073/pnas.79.17.5171. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Blume A., Wittebort R. J., Das Gupta S. K., Griffin R. G. Phase equilibria, molecular conformation, and dynamics in phosphatidylcholine/phosphatidylethanolamine bilayers. Biochemistry. 1982 Nov 23;21(24):6243–6253. doi: 10.1021/bi00267a032. [DOI] [PubMed] [Google Scholar]
- Caffrey M., Bilderback D. H. Kinetics of the main phase transition of hydrated lecithin monitored by real-time X-ray diffraction. Biophys J. 1984 Mar;45(3):627–631. doi: 10.1016/S0006-3495(84)84201-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Caffrey M., Feigenson G. W. Fluorescence quenching in model membranes. 3. Relationship between calcium adenosinetriphosphatase enzyme activity and the affinity of the protein for phosphatidylcholines with different acyl chain characteristics. Biochemistry. 1981 Mar 31;20(7):1949–1961. doi: 10.1021/bi00510a034. [DOI] [PubMed] [Google Scholar]
- Caffrey M., Feigenson G. W. Influence of metal ions on the phase properties of phosphatidic acid in combination with natural and synthetic phosphatidylcholines: an X-ray diffraction study using synchrotron radiation. Biochemistry. 1984 Jan 17;23(2):323–331. doi: 10.1021/bi00297a023. [DOI] [PubMed] [Google Scholar]
- Caffrey M. Kinetics and mechanism of the lamellar gel/lamellar liquid-crystal and lamellar/inverted hexagonal phase transition in phosphatidylethanolamine: a real-time X-ray diffraction study using synchrotron radiation. Biochemistry. 1985 Aug 27;24(18):4826–4844. doi: 10.1021/bi00339a017. [DOI] [PubMed] [Google Scholar]
- Chapman D., Urbina J. Biomembrane phase transitions. Studies of lipid-water systems using differential scanning calorimetry. J Biol Chem. 1974 Apr 25;249(8):2512–2521. [PubMed] [Google Scholar]
- Chen S. C., Sturtevant J. M., Gaffney B. J. Scanning calorimetric evidence for a third phase transition in phosphatidylcholine bilayers. Proc Natl Acad Sci U S A. 1980 Sep;77(9):5060–5063. doi: 10.1073/pnas.77.9.5060. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hauser H., Pascher I., Pearson R. H., Sundell S. Preferred conformation and molecular packing of phosphatidylethanolamine and phosphatidylcholine. Biochim Biophys Acta. 1981 Jun 16;650(1):21–51. doi: 10.1016/0304-4157(81)90007-1. [DOI] [PubMed] [Google Scholar]
- Janiak M. J., Small D. M., Shipley G. G. Nature of the Thermal pretransition of synthetic phospholipids: dimyristolyl- and dipalmitoyllecithin. Biochemistry. 1976 Oct 19;15(21):4575–4580. doi: 10.1021/bi00666a005. [DOI] [PubMed] [Google Scholar]
- Luna E. J., McConnell H. M. Multiple phase equilibria in binary mixtures of phospholipids. Biochim Biophys Acta. 1978 Jun 2;509(3):462–473. doi: 10.1016/0005-2736(78)90240-7. [DOI] [PubMed] [Google Scholar]
- McIntosh T. J. Differences in hydrocarbon chain tilt between hydrated phosphatidylethanolamine and phosphatidylcholine bilayers. A molecular packing model. Biophys J. 1980 Feb;29(2):237–245. doi: 10.1016/S0006-3495(80)85128-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schroit A. J., Madsen J. W. Synthesis and properties of radioiodinated phospholipid analogues that spontaneously undergo vesicle-vesicle and vesicle-cell transfer. Biochemistry. 1983 Jul 19;22(15):3617–3623. doi: 10.1021/bi00284a012. [DOI] [PubMed] [Google Scholar]
- Shimshick E. J., McConnell H. M. Lateral phase separation in phospholipid membranes. Biochemistry. 1973 Jun 5;12(12):2351–2360. doi: 10.1021/bi00736a026. [DOI] [PubMed] [Google Scholar]
- Tamura A., Yoshikawa K., Fujii T., Ohki K., Nozawa Y., Sumida Y. Effect of fatty acyl chain length of phosphatidylcholine on their transfer from liposomes to erythrocytes and transverse diffusion in the membranes inferred by TEMPO-phosphatidylcholine spin probes. Biochim Biophys Acta. 1986 Feb 27;855(2):250–256. doi: 10.1016/0005-2736(86)90171-9. [DOI] [PubMed] [Google Scholar]
- Wilkinson D. A., Nagle J. F. Metastability in the phase behavior of dimyristoylphosphatidylethanolamine bilayers. Biochemistry. 1984 Mar 27;23(7):1538–1541. doi: 10.1021/bi00302a030. [DOI] [PubMed] [Google Scholar]
