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Do, 16:05-17:35, SoSe 2012 Bert Nickel (nickel@lmu.de)

Biomembranes – a teaser • defining the cell (what’s cell, what’s not)

• blood cells are able to squeeze through narrow pores

• impermeable barriers to ions; allows for build-up of chemical and

electrical gradients (battery of the cell, life is non-equilibrium)

• the outer cell wall is decorated by macro molecules (sugars), which are the cells ID (who am I – who are you)

• the immune system relies on cell-cell contacts between T-cells and cells to be sampled. Signalling involved lipid rearrangements

• the lung is a huge surface tension problem moderated by surfactants

• membranes are the cables of the nervous system, vesicles are the spark generater

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membranes wrap everything

blood cells

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the impermeable membrane

Walther Nernst 1864 - 1941

sugar coats identify cells

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immune system: cell-cell contacts of killer cells

genetic program starts

the lungs: surface tension at work

Pulmonary surfactant is present in the epithelial lining of alveoli. Its main function is to lower the surface tension between air and alveolar fluid and thus to prevent alveolar collapse at end of the expiration (Clements 1977)... Pulmonary surfactant consists of lipids (90–95%) and four surfactant proteins (SP-A, SP-B, SP-C, and SP-D, 5–10%).

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neurons and synapses

50nm

why is this physics ?

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from simple to complex

identify the essential elements, learn about their interactions

Self assembled monolayers

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Molecular crystals and thin films

use whatever experimental tools it needs

Max von Laue 1879 - 1960

today ESRF, a 3rd generation synchrotron

tomorrow: Max-von-Laue symposium

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experimental methods covered

• diffraction

• fluorescence microscopy FRET, FCS, FRAP

• light scattering

• patch clamp

• vesicle preparation

• Langmuir trough

• …

theoretical concepts

thermodynamics mechanics, forces

electrochemistry hydration forces

fluctuations random motion, diffusion

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http://www.physik.lmu.de/lehre/vorlesungen/sose_12/membranes/index.html

Literature

• Ole G. Moritsen Life - as a matter of fat. The emerging science of lipidomics

• Jacob Israelachvili Intermolecular & surface forces

• Erich Sackmann Einführung in die Biophysik