1. Department of Chemistry, Humboldt-Universitaet zu Berlin, Brook-Taylor Strasse 2, 12489 Berlin, Germany, Proteome Factory AG, Dorotheenstrasse 94, 10117 Berlin, Germany, and CCR/Institute of Pharmacology and Toxicology, Charité University Medicine, Hessische Strasse 3-4, 10115 Berlin, Germany