Arthur Kornberg. Portrait of Arthur Kornberg (born 1918), American biochemist. Kornberg specialised in the study of enzymes. He discovered the reactions that created two important coenzymes, flavin adenine dinucleotide (FAD) and nicotinamide adenine dinucleotide (NAD). In 1956 Kornberg isolated deoxyribonucleic acid (DNA) polymerase I and showed that it synthesised DNA from nucleotide molecules. He also showed that this reaction only took place outside cells if some natural DNA was present to act as a template and primer. In 1959 Kornberg shared the Nobel prize for medicine with S. Ochoa. Photographed in 1987.