Koji Nakanishi (中西 香爾, Nakanishi Kōji, born May 11, 1925) a bioorganic and natural products chemist, is Centennial Professor Emeritus of Chemistry and former Chairman of the Chemistry Department, Columbia University.He was born in Hong Kong on May 11, 1925. He received his bachelor's degree in chemistry from Nagoya University in 1947 from Prof. Fujio Egami. Following two years of post-graduate work with Prof. Louis Fieser at Harvard University, he returned to Nagoya University where he completed his Ph.D. in 1954 with Prof. Yoshimasa Hirata. He took a position as Assistant Professor at Nagoya, and then Professor of Chemistry at Tokyo Kyoiku University. In 1963 he moved to Tohoku University in Sendai and remained there until 1969 when he joined the faculty of Columbia University. In 1980 he became Centennial Professor of Chemistry. He was Chairman of the Chemistry Department, 1987-90.He was a founding member and one of the six Directors of Research at the International Center of Insect Physiology and Ecology in Kenya, the first Director of the nonprofit Suntory Institute for Bioorganic Research (Sunbor), Osaka, and he assisted the Brazilian government to set up a center of excellence in the Amazons, the Institute of Medicinal and Ecological Chemistry with its headquarters in São Paulo. In April 2001 he was asked to start a chemistry unit within Biosphere 2, Arizona, operated by Columbia University.His research encompasses isolation, structural and bioorganic studies of bioactive compounds, retinal proteins, interaction between ligands and neuroreceptors, development of various spectroscopic methods, especially circular dichroic spectroscopy. He has published around 750 papers, and has authored, co-authored, or edited nine books on spectroscopy and natural products.Koji Nakanishi has determined the structures of over 200 biologically active animal and plant natural products, many of which are endogenous and/or the first member of a new class. These include ginkgolides from the ancient ginkgo tree, first insect molting hormones from plants, new nucleic acid bases, insect antifeedants, antibiotics, first meiosis inducing substance from starfish, crustacean molt inhibitors, shark repellents from fish, tunicate blood pigments, brevetoxins from red-tide dinoflagellates, philanthotoxin (glutamate and nicotinic acetylcholine receptor antagonist) from a wasp, and the human eye pigment involved in macular degeneration.His studies with retinal analogs and retinal proteins have made seminal contributions in understanding the structural and mechanistic basis of animal vision and phototaxis. In 2000 his research group succeeded in clarifying relative movements of the retinal and the opsin receptor throughout the visual transduction process; this is the first such study performed with G protein coupled receptors (GPCR) and will contribute in clarifying the mode of action of numerous other GPCRs. It also established the structure and biosynthesis of the fluoresc