1. Institute of Physiological Chemistry, Faculty of Veterinary Medicine, Ludwig-Maximilians-University Munich, Veterinärstrasse 13, D-80539 Munich, Germany, Institute of Experimental Physics, Department of Biophysics, Slovak Academy of Sciences, Watsonova 47, SK-01001 Kosice, Slovak Republic, Bioorganic Chemistry, Building NW1, University of Bayreuth, D-95440 Bayreuth, Germany, and Faculty of Pharmaceutical Sciences, Tokyo University of Science, Yamazaki 2641, Noda-City, Chiba 278-8510, Japan