Ivano Bertini - Professor of Chemistry and Director of the Magnetic Resonance Center of the University of Florence. His main research interests are the advancements in nuclear magnetic resonance spectroscopy, the expression and preparation of metalloproteins, their structural characterization and the investigation of their interactions with emphasis on understanding cellular processes at the molecular level. Harry B. Gray - the Arnold O. Beckman Professor of Chemistry and the Founding Director of the Beckman Institute at the California Institute of Technology. His main research interests center on inorganic spectroscopy, photochemistry, and bioinorganic chemistry, with emphasis on understanding electron transfer in proteins. For his contributions to chemistry, which include over 700 papers and 17 books, he has received the National Medal of Science from President Ronald Reagan (1986); the Linderstrøm-Lang Prize (1991); the Basolo Medal (1994); the Gibbs Medal (1994); the Chandler Medal (1999) and the Harvey Prize (2000). Edward I. Stiefel - Professor of Chemistry at Princeton University and associated faculty member of the Princeton Environmental Institute until his untimely death in summer of 2006. His research involved the role of metal ions in biological systems including: iron in marine environments, especially the iron storage and DNA protective proteins ferritin and Dps; the biological production of hydrogen by phototropic hydrogenases and theoretical studies of hydrogenase action; the role of molybdenum in biology; and aspects of metals in medicine. Joan S. Valentine -