1. Department of Chemistry, Stanford University, Stanford, California 94305, United States
2. DuPont Industrial Biosciences, 925 Page Mill Road, Palo Alto, California 94304, United States
3. Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O. Box 7015, SE-750 07 Uppsala, Sweden
4. DuPont Industrial Biosciences, Netherlands, Nieuwe Kanaal 7-S, 6709 PA Wageningen, The Netherlands