OLIGO PELDOR · Pulsed Dipolar Spectroscopy on Symmetric Oligomers

Pulse EPR distance measurements have evolved to a standard tool for generating long-range constraints for structural modelling via pulsed dipolar spectroscopy. Especially the pulsed electron−electron double resonance (PELDOR or DEER) method is becoming increasingly applied. The method is particularly promising for structural studies on different functional states of membrane proteins which are difficult to access by most biophysical methods.However, in samples of membrane proteins several approximations commonly made in data analysis might not be well met. The effect of the finite sample concentration is not necessarily as straightforward as in homogeneous solutions. Furthermore, systems of singly-labelled monomers forming trimers or higher oligomers not only allow extracting the oligomerisation state from the modulation depth, but also exhibit multi-spin effects hampering the distance analysis which are often neglected. These multi-spin effects should increase significantly with oligomeric state.In the proposed project we will address these problems and develop and validate alternative approaches to data acquisition and analysis in symmetric multi-spin systems.