dorsal/arxiv
View SchemaX-Ray Kinematography of Temperature-Jump Relaxation Probes the Elastic Properties of Fluid Bilayers
| Authors | Georg Pabst, Michael Rappolt, Heinz Amenitsch, Sigrid Bernstorff, Peter Laggner |
|---|---|
| Categories | |
| ArXiv ID | physics/0002040 |
| URL | https://arxiv.org/abs/physics/0002040 |
Abstract
The response kinetics of liquid crystalline phosphatidylcholine bilayer stacks to rapid, IR-laser induced temperature jumps has been studied by millisecond time-resolved x-ray diffraction. The system reacts on the fast temperature change by a discrete bilayer compression normal to its surface and a lateral bilayer expansion. Since water cannot diffuse from the excess phase into the interbilayer water region within the 2 ms duration of the laser pulse, the water layer has to follow the bilayer expansion, by an anomalous thinning. Structural analysis of a 20 ms diffraction pattern from the intermediate phase indicates that the bilayer thickness remains within the limits of isothermal equilibrium values. Both, the intermediate structure and its relaxation into the original equilibrium L_(alpha)-phase, depend on the visco-elastic properties of the bilayer/water system. We present an analysis of the relaxation process by an overdamped one-dimensional oscillation model revealing the concepts of Hooke's law for phospholipid bilayers on a supramolecular basis. The results yield a constant bilayer repulsion and viscosity within Hooke's regime suggesting that the hydrocarbon chains act as a buffer for the supplied thermal energy. The bilayer compression is a function of the initial temperature and the temperature amplitude, but is independent of the chain length.
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"abstract": "The response kinetics of liquid crystalline phosphatidylcholine bilayer\nstacks to rapid, IR-laser induced temperature jumps has been studied by\nmillisecond time-resolved x-ray diffraction. The system reacts on the fast\ntemperature change by a discrete bilayer compression normal to its surface and\na lateral bilayer expansion. Since water cannot diffuse from the excess phase\ninto the interbilayer water region within the 2 ms duration of the laser pulse,\nthe water layer has to follow the bilayer expansion, by an anomalous thinning.\nStructural analysis of a 20 ms diffraction pattern from the intermediate phase\nindicates that the bilayer thickness remains within the limits of isothermal\nequilibrium values. Both, the intermediate structure and its relaxation into\nthe original equilibrium L_(alpha)-phase, depend on the visco-elastic\nproperties of the bilayer/water system. We present an analysis of the\nrelaxation process by an overdamped one-dimensional oscillation model revealing\nthe concepts of Hooke\u0027s law for phospholipid bilayers on a supramolecular\nbasis. The results yield a constant bilayer repulsion and viscosity within\nHooke\u0027s regime suggesting that the hydrocarbon chains act as a buffer for the\nsupplied thermal energy. The bilayer compression is a function of the initial\ntemperature and the temperature amplitude, but is independent of the chain\nlength.",
"arxiv_id": "physics/0002040",
"authors": [
"Georg Pabst",
"Michael Rappolt",
"Heinz Amenitsch",
"Sigrid Bernstorff",
"Peter Laggner"
],
"categories": [
"physics.bio-ph"
],
"title": "X-Ray Kinematography of Temperature-Jump Relaxation Probes the Elastic Properties of Fluid Bilayers",
"url": "https://arxiv.org/abs/physics/0002040"
},
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