1 Freie Universität Berlin, Institute of Chemistry and Biochemistry, Takustr. 3, 14195 Berlin, Germany. Electronic address: beate.koksch@fu-berlin.de.
2 Max-Planck Institute for Colloids and Interfaces, Biomolecular Systems Department, Am Mühlenberg 1, 14476 Potsdam, Germany. Electronic address: peter.seeberger@mpikg.mpg.de.