1. Division of Biochemistry, Department of Chemistry University of Crete Voutes Heraklion GR‐71003 Greece
2. Max Planck Institute for Brain Research Max‐von‐Laue‐Straße 4 Frankfurt am Main D‐60438 Germany
3. Max Planck Institute for Biophysics Max‐von‐Laue‐Straße 3 Frankfurt am Main D‐60438 Germany