1. a Dept. of Physiological Chemistry , Technical University of Braunschweig , Mascheroder Weg 1, D-38124 Braunschweig, Germany
2. b National Centre for Biotechnology (GBF) , Mascheroder Weg 1, D-38124 Braunschweig, Germany
3. c Dept. of Physiological Chemistry , Technical University of Braunschweig , Mascheroder Weg 1, D-38124 Braunschweig, Germany