1. A. N. Belozersky Institute of Physico-Chemical Biology and School of Chemistry, Moscow State University, Moscow 119899, Russia, Department of Biochemistry, University of Turku, FIN-20014 Turku, Finland, Center for Ulcer Research and Education, Department of Medicine, University of California, Los Angeles, California 90073, Department of Chemistry, University of Pennsylvania, Pennsylvania 19104-6323, and Institute of Biotechnology, University of Helsinki, P.O. Box 56, FIN-00014 Helsinki, Finland