1. Department of Biochemistry, University of Turku, FIN-20014 Turku, Finland, Department of Biochemistry and Biotechnological Medicine, Via Pansini 5, University Federico II of Naples, Italy, c/o CEINGE, Centro di Ingegneria Genetica e Biotecnologie Avanzate, Naples, Italy, Department of Physiological Chemistry, Ruhr-University Bochum, 44801 Bochum, Germany, and A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia