Published in BBA - Biomembranes
The lipid phase transition of Escherichia coli was studied by high sensitivity differential scanning calorimetry. A temperature sensitive unsaturated fatty acid auxotroph was used to obtain lipids with subnormal unsaturated fatty acid contents. From these studies it was concluded that E. coli can grow normally with as much as 20% of its membrane li...
Published in BBA - Biomembranes
Bacteriorhodopsin has been reconstituted at various molar concentrations into liposomes of dimyristoyl- and also of dipalmitoylphosphatidylcholine. Differential scanning calorimetry indicates that as the protein concentration within the lipid bilayer increases, the cooperativity of the lipid phase transition is reduced, i.e. the transition is broad...
Published in BBA - Biomembranes
The structural changes accompanying the recently described sub-transition of hydrated dipalmitoylphosphatidylcholine (Chen, S.C., Sturtevant, J.M. and Gaffney, B.J. (1980) Proc. Natl. Acad. Sci. USA 77, 5060–5063) have been defined using X-ray diffraction methods. Following prolonged storage at −4°C the usual L β′ gel form of hydrated dipalmitoylph...
Published in BBA - Biomembranes
The phase behavior of aqueous dispersions of extracted lipids from Clostridium thermocellum wild-type and ethanol-tolerant C919 cells has been examined by DSC. The optimum growth temperature of this anaerobe is 60°C. The wild-type lipids exhibit a broad phase transition centered at 30°C; the C919 mutant lipids show a 10°C lower T m. The direct addi...
Detailed DSC and textural studies on HOBACPC in solid and liquid crystalline phases are presented. DSC studies have shown the existence of two solid crystalline (SC) phases in this compound. The existence and the preponderance of these SC phases depend critically on the thermal history of the sample. The thermal degradation of the material in air a...
The smectic phases of the compound 4-(2'-methylbutyl)phenyl 4'-n-octylbiphenyl-4-carboxylate (2M4P8BC) were studied by means of polarized optical microscopy, miscibility, DSC, and X-ray diffraction techniques. The phase sequence Cr ↔ G ↔ J ↔ I ↔ C ↔ A has been determined, and consequently 2M4P8BC has been shown to be the first example of a pure mat...
Published in Biochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism
sn-1 ( d) and sn-3 ( l) enantiomers of fully hydrated dimyristoylphosphatidylcholine (DMPC) were studied with a high-sensitivity differential scanning calorimeter. Main transition and pretransition temperatures and enthalpies of sn-1-DMPC were identical to those of the sn-3 isomer. Mixed liposomes consisting of both sn-1- and sn-3-DMPC were formed ...
Die Vorkristallisation von Milch- und Bitterschokoladen sowie Kakaobutter wurde untersucht. Die Kristallanteile in den vorkristallisierten Massen wurden bei verschiedenen Temperaturen über DSC-Thermoanalyse und Pulsed-NMR-Kernresonanz quantitativ bestimmt; in optimal vorkristallisierten Schokoladenmassen waren rund 5% des Fettanteiles kristallisier...
Thermoanalytische Verfahren lassen sich in vielen Bereichen zur Messung der Enthalpieaenderung von Substanzen anwenden. In der Arbeit werden Moeglichkeiten aufgezeigt, diese Methode fuer die Charakterisierung der Proteindenaturierung allgemein und der Bestimmung der Schaedigungsgrenztemperatur eines lebenden Mikroorganismus zu nutzen. Als Modellorg...
Die Kristallkeimbildung in der unterkühlten Schmelze von Kakaobutter und Milich- bzw. Bitterschokolade wurde untersucht. Mit sinkender Kühltemperatur verringert sich die Keimbildungszeit exponentiell. Durch Anwendung verschiedener Geräte (Kristallisator, Rotationsviskosimeter, Brabender-Meßkneter, DSC) wurde nachgewiesen, daß die Keimbildungsgeschw...
