born March 3, 1918, Brooklyn, N.Y., U.S.
U.S. biochemist and physician.
He studied at the University of Rochester. In 1959 he joined the faculty at Stanford University. While studying how living organisms manufacture nucleotide s, his research led him to the problem of how nucleotides are strung together to form DNA molecules. Adding radioactive nucleotides to an enzyme mixture prepared from cultures of E. coli , he found evidence of a reaction catalyzed by the enzyme that adds nucleotides to a preexisting DNA chain. He was the first to accomplish the cell-free synthesis of DNA. He shared a 1959 Nobel Prize with Severo Ochoa .