Marshall Nirenberg (1927-2010). Computer illustration of the US and german biochemists Marshall Warren Nirenberg and J. Heinrich Matthaei performing an experiment using phenylalanine (Phe) to show how to decipher the genetic code. Nirenberg studied the enzymes involved in DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) and their role in protein synthesis. From 1962 he was head of Biochemical Genetics at the US National Institutes of Health. He shared the 1968 Nobel Prize in Physiology or Medicine for his work on genetics and 'breaking the genetic code'. Matthaei is best known for his unique contribution to solving the genetic code on 15th may 1961.