Daniel E. Koshland, Jr. 1920–2007

The world has lost one of its great scientists and the University of California its most influential educator with the death of Daniel E. Koshland, Jr. on Monday, July 23, 2007. Dan’s career spanned 60 years of creative biochemical research, and he was actively planning his next experiments on the Friday before his sudden death. Those of us fortunate enough to have experienced Dan’s extraordinary personality will always remember his wisdom, sharp wit, and kindness, especially toward students and young scientists. My first encounter with Dan was in 1969 as an undergraduate student at the University of California, Berkeley, better known as Cal. I was taking his renowned biochemistry class. He invariably started his lectures with some hilarious joke or witty one liner that quickly engaged us all. However, we soon realized that Dan was both funny and very serious about science. Somehow he managed to teach us more about protein chemistry and the properties of biological macromolecules in ten weeks than we thought possible. Most memorable were his infectious enthusiasm for the subject and his depth of knowledge, which was frequently punctuated by stories of famous biochemist colleagues and their foibles. We learned from him about the flexibility of protein structures and delved deeply into enzyme catalysis, induced fit mechanisms, negative and positive cooperativity, orbital steering, and feedback control. The bold idea of induced fit came to Dan 20 years before hardcore crystallographic data proved him correct. Back then, Dan was struggling with the paradox that enzymes such as hexokinase were lousy ATPases. Yet if hexokinase and other kinases worked in a rigid “lock & key” fashion, why didn’t a water molecule attack ATP as efficiently as a sugar substrate? He reasoned that the correct sugar substrate was needed to sculpt the enzyme and thus induce the right fit, a prescient idea that is still current. My next contact with Dan was in his office when I interviewed for a coveted position as an undergraduate research fellow. I went in tongue tied and brain frozen, but he adeptly put me at ease with a few gentle words of encouragement sprinkled with his trademark humor. “It’s easy to ruin any good scientist’s career—just provide them with unlimited resources and money.”