Distance Measurements between Paramagnetic Centers by High-Field EPR

The resonance frequency of an electron is highly sensitive to the local magnetic field at the electron and can therefore be used as a probe of the electron's direct surroundings. Electron Paramagnetic Resonance (EPR or ESR) is a method by which this can be studied. The presence of a nearby electron B may cause faster relaxation of electron A, which depends on the distance between the two electrons. Performing EPR relaxation measurements at high magnetic fields (6.4 Tesla) provides the spectral resolution from which one can extract information about the distance between and orientation of electrons A and B with respect to each other.High-field EPR relaxation measurements have been performed on the electron-transfer proteins cytochrome c and cytochrome c oxidase. These proteins form a short-lived complex in which an electron is transferred from cytochrome c to its partner. The goal was to determine the structure of this transient complex. Based on extensive analysis and simulation of the data from conventional as well as high-field EPR it is proposed in this work that the two proteins do not build a single, well-defined complex, but rather form unspecific, short-lived complexes.

The author was born in Wageningen (Netherlands) in 1980. She studied Molecular Sciences in her hometown from 1998 to 2002. In 2003 she started her PhD thesis on distance measurements using EPR spectroscopy in Frankfurt, and defended it successfully in April 2007. She currently works as a postdoc at the Max Planck Institute for chemistry in Mainz.