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Gel to Liquid‐Crystalline Phase Transitions of Lipids and Membranes Isolated from Escherichia coli Cells
Author(s) -
Kato Kyoko,
Bito Yukio
Publication year - 1980
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.1980.tb02871.x
Subject(s) - differential scanning calorimetry , membrane , thermotropic crystal , membrane lipids , phosphatidylethanolamine , fatty acid , endothermic process , chromatography , phase transition , phase (matter) , biology , biochemistry , crystallography , phospholipid , chemistry , phosphatidylcholine , organic chemistry , liquid crystalline , adsorption , physics , thermodynamics , quantum mechanics
Differential scanning calorimetry (DSC) was used to examine the relationship of the gel to liquid‐crystalline phase transition of lipids to fatty acid composition with membrane lipids and spheroplast membranes isolated from cells of a wild strain and an unsaturated fatty acid auxotroph of Escherichia coli grown under various conditions. These lipids and membranes underwent thermotropic phase transitions at different temperatures depending on the thermal properties of their constituent fatty acids. The lipid phase transition occurred at higher temperatures in biomembranes than in extracted lipids. DSC thermograms of lipids synthesized by bacterial cells which were observed at a temperature scanning rate as slow as 0.3 K min ‐1 were characterized by a distinctly plain peak summit. Endothermic peaks given by samples derived from elaidic acid‐enriched cells were relatively narrow and asymmetric. The discrepancy between the transition temperatures measured with extracted lipids and with membraneous fractions, and the shape of the endothermic peaks, are discussed.