PhD defence by Martin Gudmand

Cand. scient. Martin Gudmand will give a public lecture on his thesis entitled: Phase behaviour and Enzyme Dynamics at the Lipid-Water Interface followed by an oral defence. The defence is open to the public. The thesis was submitted in May 2008.

“Single Molecule Experiments” are currently receiving a lot of interest within biophysics and biochemistry. This is motivated mainly by the wish to resolve the behaviour of individual molecules and map the distribution of values. In contrast, ensemble measurements typically yield an average value for all the molecules of the system. The monolayer technique (“Self-Assembled Lipid Monolayers at the Air-Water Interface”) is such an ensemble technique. It provides control over many of the thermodynamic variables of a lipid system. By constructing a single molecule fluorescence microscope around a monolayer setup we have been able to do single molecule fluorescence studies on well-defined lipid monolayer systems.

The first part of this talk will describe the setup, and introduce the complex morphology exhibited by a lipid (DPPC) monolayer when it undergoes pressure induced phase transitions. The enzyme Phospholipase A2 (PLA2) will also be introduced, and examples of its action on monolayers will be given.

The main part of the talk will show how two different single molecule techniques: FCS (fluorescence correlation spectroscopy) and SMT (single molecule tracking) can be used to determine the diffusion coefficient of lipid molecules and enzymes moving in the plane of the monolayer. 

Evaluation Committee:

• Professor Tommy Nylander, University of Lund, Center for Chemistry and Chemical Engineering, Lund Sweden. 
• Associate Professor Beate Klösgen, Memphys, Physiscs Department, University of Southern Denmark, Odense, Denmark. 
• Professor Klaus Bechgaard (Chairman), Department of Chemistry, University of Copenhagen, Copenhagen, Denmark.

 
Supervisors:
Professor Thomas Heimburg, Niels Bohr Institut, Bio Complexity, University of Copenhagen
Professor Thomas Bjørnholm, Nano-Science Center & Department of Chemistry, University of Copenhagen