Hans Krebs

Hans Krebs was born on 25 August 1900 in Hildesheim, Germany, and died on 22 November 1981 in Oxford, England. He studied medicine at Gottingen, Freiburg and Berlin, earned his MD at Hamburg in 1925, then spent a year training in chemistry before joining Otto Warburg's laboratory at the Kaiser Wilhelm Institute for Biology in Berlin-Dahlem in 1926, where he learned the manometric tissue-slice methods that underpinned his later work. Appointed to the medical faculty at Freiburg in 1932, he discovered the urea cycle there with Kurt Henseleit, showing how the body converts toxic ammonia into urea for excretion. In April 1933 he was dismissed from his Freiburg post under the Nazi Law for the Restoration of the Professional Civil Service, which removed Jewish and other politically targeted academics from state positions; within months Cambridge University's biochemistry department, under Frederick Gowland Hopkins, took him in, and in 1935 he moved to a lectureship at the University of Sheffield. There, in 1937, with William Arthur Johnson, he worked out the citric acid cycle, a closed loop of reactions in the mitochondria of nearly all living cells that completes the breakdown of food while extracting the energy cells use; the finding was submitted first to the journal Nature, which rejected it as too long, and was published instead in the journal Enzymologia the same year. He shared the 1953 Nobel Prize in Physiology or Medicine with Fritz Lipmann for the discovery, now taught universally as the Krebs cycle. He moved to the University of Oxford in 1954, remained there for the rest of his career, and was knighted in 1958.