Nobel Foundation · Public domain

Ernst Chain left Berlin for London in 1933 with ten pounds in his pocket, one of many Jewish scientists driven out as the Nazis rose to power. At Oxford with Howard Florey, he worked out how to isolate and concentrate the antibacterial agent in Alexander Fleming's decade-old, largely ignored penicillin mold, turning a laboratory curiosity into a usable drug; the three shared the 1945 Nobel Prize in Physiology or Medicine for it. He later founded the biochemistry department at Imperial College London.