1. Universidad de Conception, Casilla 2407, Apartado 10, Conception 3, Chile
2. Lehrbereich Biotechnologie der Universität, Paul-Ehrlich-Straße 23, D-67663 Kaiserslautern, Germany
3. Department of Organic and Bioorganic Chemistry, Lund University, P. O.Box 124, S-221 00 Lund, Sweden