1. Institute of Biochemistry, Swiss Federal Institute of Technology, ETH Center, Universitätstrasse 16, CH-8092 Zurich, Switzerland, Allegheny University of the Health Sciences, MCP, Hahnemann School of Medicine, Biochemistry Department, 2900 Queen Lane, Philadelphia, Pennsylvania 19129, and Department of Internal Medicine, Medical Policlinic, University Hospital, CH-8091 Zurich, Switzerland