Thermotropic Behavior of Structurally-Related Phospholipids and Phosphonolipid Analogs of Lung Surfactant Glycerophospholipids
| Autor: | Huicai Liu, Robert H. Notter, Joseph G. Turcotte |
|---|---|
| Rok vydání: | 1995 |
| Předmět: |
Chemistry
Hydrogen bond Stereochemistry Phospholipid Surfaces and Interfaces Glycerophospholipids Condensed Matter Physics Thermotropic crystal Medicinal chemistry chemistry.chemical_compound Differential scanning calorimetry Pulmonary surfactant Dipalmitoylphosphatidylcholine Electrochemistry General Materials Science Amine gas treating Spectroscopy |
| Zdroj: | Langmuir. 11:101-107 |
| ISSN: | 1520-5827 0743-7463 |
| Popis: | Gel to liquid crystal transition temperatures (T c ) were measured by differential scanning calorimetry for a series of synthetic analogs of naturally occurring lung surfactant glycerophospholipids at pH 2.6, 5.6, and 11.5. Compounds all had equivalent C 16 saturated chains, and included dipalmitoylphosphatidylcholine (DPPC), dipalmitoylphosphatidylethanolamine (DPPE), dihexadecylphosphatidylcholine (DHPC), dihexadecylphosphatidylethanolamine (DHPE), and eleven related phosphonolipids varying systematically in the N-head group [six ether-ether phosphonolipids (DEPN series) and five ether-amide phosphonolipids (EAPN series)]. Thermotropic behavior varied significantly with molecular structure and pH as follows: (1) DPPC, DHPC, and phosphonolipids with choline (DEPN-8, EAPN-9) or otherwise fully N-substituted head groups (DEPN-9) had transition temperatures that were highest at pH 2.6, decreased at pH 5.6, and relatively unchanged at pH 11.5; (2) DPPE, DHPE, and phosphonolipids with unsubstituted primary amine head groups (DEPN-13, EAPN-13) had much higher T c than fully N-substituted compounds at pH 2.6 and 5.6, with decreased and almost equivalent transition temperatures at pH 11.5; (3) phosphonolipids with one N-methyl substitution (DEPN-12, EAPN-12) had T c values and pH-dependence similar to unsubstituted primary amine compounds; and (4) phosphonolipids with two N-methyl substitutions (DEPN-10, EAPN-10) or two N-hydroxyethyl substitutions (DEPN-11, EAPN-11) had T c values that were lowest at pH 5.6, and increased at pH 2.6 and 11.5. These results show that phase transition temperatures increased as intermolecular hydrogen bonding between lipid head groups increased, and T c also increased as head group electrostatic repulsion and hydration decreased. Differences in molecular packing associated with chain-backbone junctional group also affected T c , which was consistently highest in ether-linked (vs ester-linked or ether-amide linked) compounds of equivalent N-head group. These molecular factors have previously been found to affect strongly the surface pressure-area isotherms of synthetic phospholipids and phosphonolipids in surface films cycled at the air-water interface |
| Databáze: | OpenAIRE |
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