Assembling a program in bioinorganic chemistry that is scientifi cally relevant, well defined, and self-consistent is not an easy task. In this attempt we decided to consider zinc enzymes, copper oxidases, cytochromes and cytochrome oxidase. The choice is in part due to the great attention that the current specialized literature devotes to these topics, which are now debated among chemists, biochemists, biophysicists, etc .. We believe that hydration reactions, hydrolytic and oxidative processes have much in common from the point of view of the reaction mechanisms, the comprehension of which represents a frontier of science. For these reasons these topics have been the subject of the NATO-ASI held at San Miniato, Pisa, Italy, from May 28 to June 8, 1982. We hope we can transfer here the main conclusions of what (we believe) was a very stimulating scientific meeting. We would like to thank the local saving bank, Cassa di Risparmio di San Miniato, for helping in many ways. The financial contribution from the European Research Office of the US Army, and from the Bruker Spectrospin s.r.l., Italy, is also acknowledged. The National Science Foundation of the United States has provided a travel grant to one of the participants from the U.S.A. We are grateful to the NATO Scientific Affairs Division which provided a grant to finance this Institute."

Assembling a program in bioinorganic chemistry that is scientifi cally relevant, well defined, and self-consistent is not an easy task. In this attempt we decided to consider zinc enzymes, copper oxidases, cytochromes and cytochrome oxidase. The choice is in part due to the great attention that the current specialized literature devotes to these topics, which are now debated among chemists, biochemists, biophysicists, etc .. We believe that hydration reactions, hydrolytic and oxidative processes have much in common from the point of view of the reaction mechanisms, the comprehension of which represents a frontier of science. For these reasons these topics have been the subject of the NATO-ASI held at San Miniato, Pisa, Italy, from May 28 to June 8, 1982. We hope we can transfer here the main conclusions of what (we believe) was a very stimulating scientific meeting. We would like to thank the local saving bank, Cassa di Risparmio di San Miniato, for helping in many ways. The financial contribution from the European Research Office of the US Army, and from the Bruker Spectrospin s.r.l., Italy, is also acknowledged. The National Science Foundation of the United States has provided a travel grant to one of the participants from the U.S.A. We are grateful to the NATO Scientific Affairs Division which provided a grant to finance this Institute."

Numerous investigations over the years have illustrated the importance of physical methods, especially magnetic resonance, in the elucidation of the electronic ground states of 3d transition metal ion complexes. The results of these studies coupled with investigations on model compounds are being extended in very meaningful ways to provide electronic structural information in biological systems. In systems not readily amenable to investiga- tion by single crystal X-ray diffraction these methods provide structural information as well. It was felt that a NATO Advanced Study Institute that brought together experts in theoretical aspects of magnetic resonance, experts in biology and experts in both areas would be extremely profitable for all parties attending the school. The enthusiastic response of the participants indicated that our objectives were accomplished to a high degree. We hope this pUblication of the proceedings will transmit, to some degree, the stimulating discussion of the Conference. The enormity of the area selected for this Conference can be appreciated by all. We the editors take full responsibility for the many omissions resulting from the imposed limitations of time and resources. Florence, July 1979 I. Bertini R. S. Drago PARTICIPANTS Andersen, J. P. Institute of Medical Biochemistry - University of Aarhus DK-8000 Aarhus C Denmark Andersson, I. Fachbereich 15. 2, Analytische und Biologische Chemie, Universitat des Saarlandes - D-6600 Saarbrucken 11 F. R. G. Basosi, R.