1. Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, Post Office Box 7, H-1518 Budapest, Hungary, Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, Post Office Box 49, H-1525 Budapest, Hungary, Mass Spectrometry Facility at the Biological Research Center, Hungarian Academy of Sciences, Post Office Box 521, H-6701 Szeged, Hungary, and Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California...