of Health, had noticed his paper and invited him to join the research team at the Nutrition Laboratory of the NIH. From 1942 to 1945, Kornberg's work was the feeding of specialized diets to rats to discover new vitamins. Research and career The feeding of rats was boring work, and Kornberg became fascinated by enzymes. He transferred to Dr Severo Ochoa's laboratory at New York University in 1946, and took summer courses at Columbia University to fill out the gaps in his knowledge of organic and physical chemistry while learning the techniques of enzyme purification at work. He became Chief of the Enzyme and Metabolism Section at NIH from 1947–1953, working on understanding of ATP production from NAD and NADP. This led to his work on how DNA is built up from simpler molecules. While working at NIH, he also researched at Washington University in St. Louis (in the lab of Carl Ferdinand Cori and Gerty Cori in 1947), and the University of California, Berkeley (in the lab of Horace Barker in 1951). In 1953 he became Professor and Head of the Department of Microbiology, Washington University in St. Louis, until 1959. Here he continued experimenting with the enzymes which created DNA. In 1956 he isolated the first DNA polymerizing enzyme, now known as DNA polymerase I. This got him elected to the United States National Academy of Sciences in 1957 and won him the Nobel prize in 1959. In 1960, he was elected to the American Philosophical Society, received a LL.D. again from City College and a D.Sc. at the University of Rochester in 1962. He became Professor and Executive Head of the Department of Biochemistry, Stanford University, in 1959. In an interview in 1997, Arthur Kornberg (referring to Josh Lederberg) said: "Lederberg really wanted to join my department. I knew him; he's a genius, but he'd be unable to focus and to operate within a small family group like ours, and so, I was instrumental in establishing a department of genetics [at Stanford] of which he would be chairman." Kornberg's mother died of gas gangrene from a spore infection after a routine gall bladder operation in 1939. This started his lifelong fascination with spores, and he devoted some of his research efforts to understanding them while at Washington University. From 1962 to 1970, in the midst of his work on DNA synthesis, Kornberg devoted half his research effort