The scientific community, in particular those studying the properties and functions of the cytochromes P450, recently lost a great friend, teacher, and leader. On January 16, 1996 Professor Ryo Sato died of cancer in Osaka, Japan at the age of 72. In 1962, Ryo Sato with Tsuneo Omura identified P450 as a hemoprotein and described many of its biochemical properties. This seminal study ranks tenth in the Citation Index of papers published. Ryo Sato served as an Editor of Archives of Biochemistry and Biophysics from 1970-80 and served to foster this journal as the one of choice for publication by authors of many studies characterizing the cytochromes P450.
Ryo Sato was trained in organic chemistry and biochemistry at the University of Tokyo. He moved to Nagoya to do post-doctoral research with Professor Egami where he discovered the role of cytochrome b1 in anaerobic nitrate respiration of E. coli. It was these studies that set his interest in cytochromes. Following an appointment as Assistant Professor at Kanazawa University (1951-57) he moved to the Institute for Protein Research, University of Osaka, where he advanced to the position of Director (1985-87). Since his retirement he has been associated with the Japan Ciba-Geigy Foundation.
In 1953 Ryo Sato went to Stockholm, Sweden to work with Professor Hugo Theorell on the characterization of cytochrome b1. On his return to Japan in 1955 he spent seven months at the Johnson Research Foundation, University of Pennsylvania. It was during this visit that we worked together examining the properties of a unique cytochrome (b4) that Ryo had purified from a halotolerant bacterium originally isolated from the skin of a whale. A bond of friendship developed that weathered both collaborative and competitive research activities for over forty-one years.
Sato was aware of the historic finding made at the Johnson Foundation at that time and reported by Martin Klingenberg (Arch. Biochem. Biophys. 75, 376-386, 1958) of a spectrophotometric curiosity present in rat liver microsomes that bound carbon monoxide to give an absorbance band at 450 nm. As Ryo says, "This was a surprise to me since I had not known that liver microsomes contain a cytochrome. When I knew this fact, I immediately determined to work on this system upon my return to Japan and look for a novel energy-yielding reaction that should be associated with it." Rather than discovering a new pathway for ATP synthesis in microsomes, Ryo Sato, together with Tsuneo Omura, set the stage for the subsequent explosion of information on the function and properties of cytochrome P450.
The intervening years have seen the number of P450s expand to over 500 now cloned and sequenced. The many roles of P450s in biology and medicine now include the important topics of drug metabolism, fatty acid -oxidation, activation of chemicals initiating carcinogenesis, and vitamin D hydroxylation reactions as well as the enzymatic reactions associated with the pigments of flowers, the flavorants of spices, and the resistance to pesticides by insects, to name but a few examples. We owe much of our knowledge of the P450s involved in these reactions to Ryo Sato.
Sato was a quiet and modest man whose incisive experiments frequently led the way through the maze of unknowns associated with studies of P450s. He had an encyclopedic knowledge of work done and a generosity in sharing this knowledge with others. His gentle, but sometimes critical way, of guiding students and colleagues, has made him a role model as both scientist and mentor. In 1985 Sato received the Imperial Award of the Japan Academy from Emperor Hirohito for his contributions to science.
I write this on behalf of the many friends and collegues of Ryo Sato.
Each of us has our fond memories of Ryo. Whether it was the late evenings of
discussion, sharing an exciting new finding, or comparing our stamp
collections and the wonders of our grandchildren, each of us will remember
this great man in our own special way. He will be greatly missed by his
friends and colleagues.
Ronald W. Estabrook
March 25, 1996