1. Faculty of Life Sciences; Institute of Biochemistry; University of Leipzig; Bruederstrasse 34 04103 Leipzig Germany
2. Department of Biological Sciences; Bridge Institute; University of Southern California; 1002 Childs Way MCB 317 Los Angeles CA 90089-3502 USA
3. Department of Chemistry; Bridge Institute; University of Southern California; 1002 Childs Way MCB 317 Los Angeles CA 90089-3502 USA