Todd, Sir Alexander Robertus, 1907–97, Scottish biochemist, Ph.D., Univ. of Frankfurt am Main, 1931; Oxford, 1933. Todd held posts at Edinburgh Univ. (1934–36), the Lister Institute of Preventive Medicine, Chelsea (1936–37), the Univ. of London (1937–38), and the Univ. of Manchester (1938–44). He then taught at Cambridge, where he was a professor from 1944 to 1971. In 1957 Todd was awarded the Nobel Prize in Chemistry for his work on nucleotides and nucleotide coenzymes. He is credited with establishing the chemical makeup of these compounds, which form the structural units of DNA and RNA (see nucleic acid).