1990 Fiscal Year Final Research Report Summary
Calorimetric Investigation of the Stability of Phospholipid-Vesicles
| Project/Area Number |
01470013
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
物理化学一般
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| Research Institution | Okayama University of Science, Department of Biochemistry |
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Principal Investigator |
KODAMA Michiko Okayama Univ of Science. Associate Professor, 理学部, 助教授 (40101282)
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| Co-Investigator(Kenkyū-buntansha) |
SUNAMOTO Junzo Kyoto Univ. Professor, 工学部, 教授 (80037811)
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| Project Period (FY) |
1989 – 1990
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| Keywords | differential scanning calorimetry, / vesicle / gel-liquid crystal transition / thermodynamic Stability / dimyristoylphosphatidylcholine (DMPC) / dimyristoylphosphatidylglyserol (DMPG) |
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| Research Abstract |
Phospholipids are one of the main constituent of cell membranes. The characteristic property of the phospholipid is found to form molecular assemblies, so-called vesicle (liposome), in the presence of water. In this study, thermodynamic stability of vesicles of phospholipid was investigated by high sensitivity differential scanning calorimetry. A multilamellar vesicle (MLV) of dimyristoylphosphatidylcholine (DMPC) was changed into a small unilamellar vesicle (SUV) passing through a large unilamellar vesicle (LUV) by a sonication. The enthalpy change as well as the transition temperature associated with the gel-liquid crystal transition of these vesicles increased in the order SUV LUV MLV. This fact indicates that a more curved surface of the vesicle induces a more tightly packed structure of the gel phase.
Taking into account the difference in the enthalpy value of the gel phases among three vesicles, the SUV was kept at a temperature around 4 ^ﾟC and was revealed to finally transform into the MLV on the way to the LUV. This finding suggests that the thermodynamic stability of three vesicles increases in the order SUV LUV MLV. Contrary to this result, the SUV composed of dimyristoylphosphstidylglyserol (DMPG) having a negative charge transformed into a unilamellar vesicle at a temperature above the gel-liquid crystal transition. The difference in the thermodynamic stability of the vesicles is now under consideration, focusing on the charge of phospholipids.
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