Niels Bohr Institutet > Kalender - det sker på NBI > 2010 > PhD defense by Julia Preu

PhD defense by Julia Preu

Title: Structural changes in charged membrane model systems

Lung surfactant and bacterial cell membranes are rich in charged lipids, an example is the short-chained anionic phospholipid dimyristoylphatidylglycerol. Particular interesting about this lipid is a complex melting behaviour accompanied by changes in the optical and viscous behaviour, limited by the amount of salt in the buffer. So far it was not possible to get a handle on the underlying morphological changes and the particular driving forces. This challenge was mainly addressed by means of scattering techniques using light, x-rays and neutrons as sources of radiation. To be highlighted is the use of a combination of rheology and small angle neutron scattering, allowing to trace structural changes under the influence of shear. Together with the application of differential scanning calorimetry and rheology a decreased degree of bilayer undulations could be shown, especially in comparison to analog zwitterionic lipids. 

In addition the role of charges for the interaction of membrane-active compounds with the membrane will be addressed, comparing the interaction of the blood pressure regulating petide-hormone Angiotensin II, the drug Losartan and its active derivate E-3174 with model membranes. For Angiotensin II a concentration dependent binding to the membrane is shown. Losartan and E-3174, even though quite similar in their molecular structure exhibit differences in their way of binding to the membrane, that for all three compounds may contribute to their in vivo function. 

Supervisor: Thomas Heimburg