1. Institute of Biochemistry Heinrich Heine University Universitätsstrasse 1 40225 Düsseldorf Germany
2. Institute of Biotechnology RWTH Aachen University Worringerweg 3 52074 Aachen Germany
3. DWI-Leibniz Institute for Interactive Materials Forckenbeckstraße 50 52056 Aachen Germany
4. Present address: Carl R. Woese Institute for Genomic Biology University of Illinois at Urbana-Champaign 1206 West Gregory Drive Urbana Il 61801 USA
5. Department of Bioorganic Chemistry Leibniz Institute of Plant Biochemistry Weinberg 3 06120 Halle Germany
6. Institute of Molecular Enzyme Technology Heinrich Heine University and Institute of Bio- and Geosciences IBG-1 Biotechnology, Forschungszentrum Jülich GmbH 52426 Jülich Germany