1. Contribution from VTT Biotechnology, P.O. Box 1500, FIN-02044 VTT, Espoo, Finland, Laboratory of Biochemistry, State University of Ghent, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium, Laboratory for Organic Chemistry, Swiss Federal Institute of Technology, ETH-Zentrum, Universitätsstrasse 16, CH-8092 Switzerland, Department of Paper Science, UMIST, P.O. Box 88, Sackville Street, Manchester M60 1QD, England, and Department of Cell and Molecular Biology, Uppsala University, Biomedical Center Box 596, S...