1. Institute
for Organic Chemistry and Biochemistry, Technische Universität Darmstadt, 64287 Darmstadt, Germany
2. Merck KGaA, Frankfurterstrasse
250, 64293 Darmstadt, Germany
3. Department
of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, United States
4. Wyss Institute for Biologically Inspired Engineering, Boston, Massachusetts 02115, United States