Evaluation of the thermal coefficient of the resistance to fluorophore rotation in model membranes
| Autor: | Suzanne Scarlata |
|---|---|
| Rok vydání: | 1989 |
| Předmět: |
Phase transition
Fluorophore Chemistry Phosphatidylethanolamines Bilayer Enthalpy Biophysics Analytical chemistry Hexagonal phase Models Theoretical chemistry.chemical_compound Liquid crystal Phase (matter) Liposomes Phosphatidylcholines Solvents Thermodynamics Dimyristoyl Lecithin Dimyristoylphosphatidylcholine Mathematics Research Article |
| Zdroj: | Biophysical Journal. 55:1215-1223 |
| ISSN: | 0006-3495 |
| DOI: | 10.1016/s0006-3495(89)82917-0 |
| Popis: | The thermal coefficient of the frictional resistance to fluorophore rotation (b), a parameter related to the change in the local viscosity with temperature, was determined for anthroyloxy-fatty acid probes in micelles and dimyristoyl lecithin (DMPC) and dioleoyl lecithin (DOPC) unilamellar and multilamellar vesicles. The value of b and the percent change in anisotropy with temperature (%dA/dT) remained constant with membrane depth and only depended on composition. These parameters were also the same when either in-plane, or in-plane and out-of-plane fluorophore motions were observed. This result indicates that the membranes expand isotropically. The magnitude of b was found to be primarily dependent on the packing of the hydrocarbon chains with higher b values relating to more closely-packed chains. b was responsive to the gel to liquid crystal phase transition of DMPC and the bilayer to hexagonal phase transition of egg-phosphatidylethanolamine. When the enthalpy values for the fluorophore transfer from one phase to another are calculated, the values are larger than those measured by calorimetry and reflect a discrepancy between the microscopic enthalpy experienced by the fluorophore due to a change in environment versus the macroscopic enthalpy of the system as a whole. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|