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Phase transitions, hydration, and sp...

Mansour, Heidi.

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Phase transitions, hydration, and spreading of phospholipid bilayers and monolayers at the air-water interface.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Phase transitions, hydration, and spreading of phospholipid bilayers and monolayers at the air-water interface./
作者:	Mansour, Heidi.
面頁冊數:	332 p.
附註:	Source: Dissertation Abstracts International, Volume: 64-11, Section: B, page: 5471.
Contained By:	Dissertation Abstracts International64-11B.
標題:	Health Sciences, Pharmacy. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3113759

Phase transitions, hydration, and spreading of phospholipid bilayers and monolayers at the air-water interface.
Mansour, Heidi.

Phase transitions, hydration, and spreading of phospholipid bilayers and monolayers at the air-water interface. - 332 p.

Source: Dissertation Abstracts International, Volume: 64-11, Section: B, page: 5471.

Thesis (Ph.D.)--The University of Wisconsin - Madison, 2003.

This study has shown that relationships exist between phospholipid bilayer and monolayer phase transitions, and their ability to spread as monolayers at the air-water interface. Using various derivatives of phosphatidylcholine (PC), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidic acid (PA), and phosphatidylinositol (PI), it has been shown by measurements of the equilibrium spreading pressure, πe, that above T m, the gel-to-liquid crystalline phase transition temperature, all phospholipids spread to about 45 mN/m and collapse (πc) as monolayers at the same surface pressure. At temperatures below Tm, PC and PG exhibit a drop in πe to values ≤0.2 mN/m, whereas πc remains equal to about 45 mN/m. This suggests that PC and PG monolayers collapse to a metastable bilayer structure. PE and PA, in contrast, below Tm, in the gel phase, exhibit limited spreading to πe values of 0.2 mN/m «πe« 45 mN/m; however, πe still equals πc. It is concluded that such phenomena result from the strong tendencies of these headgroups to exhibit lateral interactions via hydrogen-bonding or electrostatic interaction. Thermotropic temperature-composition phase diagrams of binary mixtures of DPPC with PE, PG, and PA, reveal significant effects of headgroup interactions, whereby spreading of DPPC only occurs when such systems are fully or partially in the liquid-crystalline phase.Subjects--Topical Terms:

1017737
Health Sciences, Pharmacy.

Phase transitions, hydration, and spreading of phospholipid bilayers and monolayers at the air-water interface.
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245 1 0 $a Phase transitions, hydration, and spreading of phospholipid bilayers and monolayers at the air-water interface.
300 $a 332 p.
500 $a Source: Dissertation Abstracts International, Volume: 64-11, Section: B, page: 5471.
500 $a Supervisor: George Zografi.
502 $a Thesis (Ph.D.)--The University of Wisconsin - Madison, 2003.
520 $a This study has shown that relationships exist between phospholipid bilayer and monolayer phase transitions, and their ability to spread as monolayers at the air-water interface. Using various derivatives of phosphatidylcholine (PC), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidic acid (PA), and phosphatidylinositol (PI), it has been shown by measurements of the equilibrium spreading pressure, πe, that above T m, the gel-to-liquid crystalline phase transition temperature, all phospholipids spread to about 45 mN/m and collapse (πc) as monolayers at the same surface pressure. At temperatures below Tm, PC and PG exhibit a drop in πe to values ≤0.2 mN/m, whereas πc remains equal to about 45 mN/m. This suggests that PC and PG monolayers collapse to a metastable bilayer structure. PE and PA, in contrast, below Tm, in the gel phase, exhibit limited spreading to πe values of 0.2 mN/m «πe« 45 mN/m; however, πe still equals πc. It is concluded that such phenomena result from the strong tendencies of these headgroups to exhibit lateral interactions via hydrogen-bonding or electrostatic interaction. Thermotropic temperature-composition phase diagrams of binary mixtures of DPPC with PE, PG, and PA, reveal significant effects of headgroup interactions, whereby spreading of DPPC only occurs when such systems are fully or partially in the liquid-crystalline phase.
520 $a Studies with the cationic hydrophobic peptide, KL4, shown to enhance spreading of certain DPPC/POPG binary mixtures, reveal that it possesses predominantly β-sheet conformation in the solid state and α-helix in solution. In the monolayer state, KL4 exists predominantly in the β-sheet conformation, with some random structure present; both of which impart flexibility for orientation of the lysine residues towards water and the leucine residues towards air.
520 $a To gain an understanding of the hydration of the various phospholipid headgroups, water vapor sorption studies were conducted. It was shown that such sorption was primarily determined by the physical state of the bilayer, as reflected in its values of Ts and Tm as a function of relative humidity, inter-and intea-bilayer interactions, and the resulting accessibility of water-binding sites. Break points in the various isotherms correspond to relative humidities where major changes in bilayer phases are expected to occur.
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650 4 $a Biophysics, Medical. $3 1017681
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710 2 0 $a The University of Wisconsin - Madison. $3 626640
773 0 $t Dissertation Abstracts International $g 64-11B.
790 1 0 $a Zografi, George, $e advisor
790 $a 0262
791 $a Ph.D.
792 $a 2003
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