1. Max-Planck Research Unit, Enzymology of Protein Folding, Weinbergweg 22, D-06120 Halle/Saale, Germany, Hans-Knöll-Institute of Natural Products Research, Beutenbergstrasse 11, D-07745 Jena, Germany, and Department of Maxillo-Facial and Plastic Surgery, Friedrich-Schiller-University, Bachstrasse 18, D-07743 Jena, Germany