Chain, Sir Ernst Boris (1906–1979), a British biochemist. In the late 1930's, he and the British pathologist Howard W. Florey developed a method for concentrating and purifying penicillin. They also demonstrated penicillin's antibiotic action, which led to its development as a drug. For this work, Chain shared the 1945 Nobel Prize in physiology or medicine with Florey and the discoverer of penicillin, Alexander Fleming.

Chain was born in Berlin and graduated from Friedrich Wilhelm University there. In 1933 he went to England, where he did research and taught at Cambridge and Oxford universities. He was scientific director of a research center for chemical microbiology in Rome from 1948 to 1961 and a professor at the University of London, 1961–73. He was knighted in 1969.