徳島大学 教育・研究者情報データベース(EDB)

1. 徳島大学.工学部.生物工学科.生物機能工学講座

1. 金品 昌志

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2. (英) Ichimori Hayato

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3. (英) Hata Takashi

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4. 松木 均([徳島大学.大学院社会産業理工学研究部.生物資源産業学域.応用生命系.応用生物資源学分野]/[徳島大学.生物資源産業学部.生物資源産業学科.応用生命講座])

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(英) Barotropic phase transitions of dioleoylphosphatidylcholine and stearoyl-oleoylphosphatidylcholine bilayer membranes

(英) In order to understand the effect of cis unsaturation on the thermotropic and barotropic phase behavior of phospholipid bilayer membranes, the phase transitions of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC), 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) bilayer membranes were observed by high-pressure optical method. With respect to DOPC bilayer membrane, the so-called main transition between the liquid crystalline (Lalpha) and the lamellar gel (Lbeta) phases was observed in water at above 0 degrees C under high pressure, in addition to the transition between the Lalpha and the lamellar crystalline (L(C)) phases in 50% aqueous ethylene glycol. The pressure of main transition increased linearly with an increase in temperature. Extrapolation of temperature (T)-pressure (P) phase boundary to ambient pressure suggests the temperature of the main transition to be -40.3 degrees C, which has never been found by the DSC method. On the other hand, the temperature of L(C)/Lalpha phase transition in 50% aqueous ethylene glycol was found to be -12.0 degrees C at ambient pressure. The main transition temperatures for DSPC, SOPC and DOPC are 55.6, 6.7 and -40.3 degrees C, respectively, at ambient pressure. The substitution of cis unsaturated chain for saturated chains of DSPC brings about the depression of the main transition temperature by about 48 (+/-1) degrees C for each chain. The volume changes (deltaV) associated with the transitions were calculated from the transition enthalpy (deltaH) and the slope of T-P diagram (dT/dP) by means of the Clapeyron-Clausius equation. The value of deltaV for the main transition of SOPC bilayer membranes was reduced to half the volume change for DSPC bilayers, which means the introduction of the cis double bond in the acyl chain of lipids brings about the reduction of deltaV because of the disordered packing of unsaturated chains in the gel phase of lipid bilayer membranes.

(日) 脂質二分子膜の相挙動におよぼすシス位の不飽和結合の影響を調べるために，ジオレオイルホスファチジルコリンとステアロイル-オレオイルホスファチジルコリン二分子膜の相転移を高圧光透過法で観測した．飽和アシル鎖へのシス不飽和結合の導入により大幅な相転移温度降下が見られた．飽和アシル鎖リン脂質と相転移体積を比較して，シス不飽和結合の導入はゲル相内の秩序低下を引き起こし，転移体積値の減少をもたらす．

1. (英) Biophysical Phenomena
2. (英) Biophysics
3. (英) Ethylene Glycol
4. (英) Gels
5. (英) Lipid Bilayers
6. (英) Phosphatidylcholines
7. (英) Pressure
8. (英) Stereoisomerism
9. (英) Temperature
10. (英) Thermodynamics
11. (英) Water

1. (英) Article.Affiliation: Department of Biological Science and Technology, Faculty of Engineering, The University of Tokushima, Japan.

2. (英) Article.PublicationTypeList.PublicationType: Journal Article