Structural Biochemistry/Nobuhiko Katunuma

Professor Nobuhiko Katunuma (1926-November 11, 2013) was one of the world’s leading scientists specialized in proteolysis in general and cysteine proteinases and their corresponding inhibitors in particular. As a renowned scientist, Professor Katunuma’s research interest is related to the medical and biomedical field as his great uncle, Professor Seizo Katsunuma, the President of Nagoya University, had told him ‘Biochemists working at Medical Schools should contribute in the fight against diseases in man’. His scientific contribution was rewarded with the ‘1990 National Violet Ribbon Decoration for Scientists and Artists’ award. Besides being a successful researcher, Professor Katunuma is also an inspirational colleague and dedicated mentor. His passion for science and intrigued ideas always provoke his coworkers. He usually observes his students’ experiment closely and also involves himself in these experiments to enhance his scientific sense even further. Nowadays, more than 30 researchers who had been Professor Katunuma’s mentee have become Professors or Laboratory Heads or even established their own laboratory. Outside his love for structural chemistry, Professor Katunuma is also interested in photography, music and Kendo, or Japanese sword fencing.

Biography
Professor Nobuhiko Katunuma was born in 1926 in Nagasaki, Japan. He graduated from the School of Medicine at Nagoya University in 1953. After earning his Doctor of Philosophy in medical sciences, he completed his Postdoctoral with Professor Hugo Theorell at the Nobel Institute in Stockholm, Sweden. After that, he moved back to Japan and became an Associate Professor at the Institute of Protein Research, Osaka University. In 1963, he moved to the Institute of Enzyme Research, School of Medicine at Tokushima University. With his widely successful scientific career and dedication to young researchers, Professor Katunuma was promoted to be the Director of the Institute since 1971 and also served as Dean of the Medical School at Tokushima University from 1980 to 1982. In 1992, he retired from Tokushima University and continued his research at the Institute for Health Sciences, at Tokushima Bunri University.

Academic Career
During the first 30 years at Tokushima University, Professor Katunuma’s main research was about the enzymes involved in vitamin B6 metabolism and their intracellular protein turnover. Together with his colleague Mitsuko Okada, he discovered mitochondrial glutamicoxalacetic transaminase and the urea cycle glutaminase isoenzymes. Later on, with his colleague Yasuhiro Kuroda, he established the enzymes’ functions in the hepatocarcinogenesis.

In 1971, he discovered the acceleration of pyridoxal enzyme turnover in animals with vitamin B6 deficiency and the enzymes participate in proteolysis of the apoproteins. These discoveries suggested that protein degradation can be initiated by the apoprotein formation in proteolysis process. This idea provoke further research into the initiation of various biochemical pathways by limited proteolysis, such as prothrombin activation by mast cell tryptase histamine release by mast cell chymase, and initiation of influenza virus entry by tryptase Clara. In his later years at Tokushima University, he also conducted a research project specialized in the role of lysosomal enzymes and their inhibitors in intracellular proteolysis. His studies on the 3D structure of protease enzyme cathepsin B in human in collaboration with Robert Huber led to his subsequent studies on chemically designed specific-inhibitors against enzyme cathepsins. With these studies, Professor Katunuma established himself as one of the pioneers in the field of structural based drug synthesis.

In 1992, after his retirement from Tokushima University, he started his second career as Professor and Director of the Institute of Health Sciences in Tokushima Bunri University. In his new position as the President of Tokushima Bunri University, Professor Katunuma actively involved in the development of new synthetic cysteine protease inhibitors, the derivatives of E-64 and the CLIK inhibitors, and studied the role of cysteine proteases in bone resorption.

Reference
Kido, Hiroshi, and Kazumi Ishidoh. "Journal of Biochemistry." Journal of Biochemistry. 148.5 (2010): 527-32. Print.