Hans Adolf Krebs

For other people with the same name, see Hans Krebs (disambiguation).
Sir Hans Adolf Krebs
Born (1900-08-25)25 August 1900
Hildesheim, Germany
Died 22 November 1981(1981-11-22) (aged 81)
Oxford, England
Citizenship Naturalised British (from 1939)
Nationality German
Fields Internal medicine, biochemistry
Institutions Kaiser Wilhelm Institute for Biology
University of Hamburg
University of Cambridge
University of Sheffield
University of Oxford
Alma mater University of Göttingen
University of Freiburg
University of Berlin
University of Hamburg
Known for Krebs cycle
Krebs–Henseleit solution
Krebs-Henseleit cycle
Glyoxylate cycle
Notable awards Albert Lasker Award for Basic Medical Research (1953)
Nobel Prize in Physiology or Medicine (1953)
Royal Medal (1954)
Copley Medal (1961)
Spouse Margaret Cicely Fieldhouse (m. 1938)
Children Paul, John, and Helen

Sir Hans Adolf Krebs (English /krɛbz/ or /krɛps/) (25 August 1900 – 22 November 1981)[1][2][3][4][5] was a German-born British physician and biochemist.[6] He was the pioneer scientist in study of cellular respiration, a biochemical pathway in cells for production of energy.[7][8] He is best known for his discoveries of two important chemical reactions in the body, namely the urea cycle and the citric acid cycle. The latter, the key sequence of metabolic reactions that produces energy in cells, often eponymously known as the "Krebs cycle", earned him a Nobel Prize in Physiology or Medicine in 1953. With Hans Kornberg, he also discovered the glyoxylate cycle, which is a slight variation of the citric acid cycle found in plants, bacteria, protists, and fungi.


Early life and education

Krebs was born in Hildesheim, Germany, to Georg Krebs, an ear, nose, and throat surgeon, and Alma Krebs (née Davidson). He was the middle of three children, older sister Elisabeth and younger brother Wolfgang. He attended the famous old Gymnasium Andreanum in his home town. Before completing his secondary school education (by six months) he was conscripted into the Imperial German Army in September 1918, during World War I. He was allowed to appear in an emergency examination for the higher school leaving certificate, which he passed in such a good grade that he suspected the examiners of being “unduly lenient and sympathetic”.[9] The war ended after two months and his conscription ended. He decided to follow his father's profession and entered the University of Göttingen in December 1918 to study medicine. In 1919 he transferred to the University of Freiburg. In 1923 he published his first technical paper on tissue staining technique, the study which he started under the guidance of his teacher Wilhelm von Mollendorf in 1920. He completed his medical course in December 1923. To obtain a medical licence he spent one year at the Third Medical Clinic in the University of Berlin. By then he turned his ambition from becoming a practising physician to medical researcher, particularly towards chemistry. In 1924 he studied at the Department of Chemistry at the Pathological Institute of the Charité Hospital, Berlin, for informal training in chemistry and biochemistry. He finally earned his M.D. degree in 1925 from the University of Hamburg.[10][11]


In 1926 Krebs joined Otto Heinrich Warburg as a research assistant at the Kaiser Wilhelm Institute for Biology in Dahlem, Berlin. He was paid a modest 4800 marks per year. After four years in 1930, with 16 publications to his credit, his mentor Warburg urged him to move on and he took up the position of Assistant in the Department of Medicine at the Municipal Hospital in Altona (now part of Hamburg). The next year he moved to the Medical Clinic of the University of Freiburg. At Freiburg he was in-charge of about 40 patients, and was at liberty to do his own research. Before a year was over at Freiburg, he, with a research student Kurt Henseleit, postulated the metabolic pathway for urea formation, now known as the ornithine cycle of urea synthesis. (Sometimes also referred to as the Krebs-Henseleit cycle. Together they also developed a complex solution for studying blood flow in arteries or perfusion ex vivo called Krebs-Henseleit solution or buffer.)[12][13] In 1932 he worked out the basic chemical reactions of urea cycle, which established his scientific reputation.

Krebs' life as a reputed German scientist came to an abrupt halt because of his Jewish ancestry. With the rise of Hitler’s Nazi Party to power, Germany decreed the Law for the Restoration of the Professional Civil Service (the removal of all non-Aryans and anti-Nazis from professional occupations). Krebs received official dismissal from his job in April 1933, and his service was terminated on 1 July. An admirer, Sir Frederick Gowland Hopkins at the University of Cambridge, immediately came to his rescue and persuaded the university to recruit Krebs to work with him in the Department of Biochemistry.[14] By July 1933 he settled in Cambridge with financial support from the Rockefeller Foundation. Although he was restricted to bring only his personal belongings, he was fortunate to be allowed to take his equipment and research samples to England, as they proved to be pivotal to his later discoveries, especially the manometer developed by Warburg specifically for the measurement of oxygen consumption in thin slices of tissues; it was the basis for his research.[15] He was appointed as Demonstrator in biochemistry in 1934 and in 1935 the University of Sheffield offered him a post of Lecturer in Pharmacology, with a more spacious laboratory and double the salary; he worked there for 19 years. University of Sheffield opened a Department of Biochemistry (now Department of Molecular Biology and Biotechnology) in 1938 and Krebs became its first Head, and eventually Professor in 1945. Krebs took over the running of the Sorby Research Institute in 1943. In 1944, the British Medical Research Council established the MRC Unit for Cell Metabolism Research at Sheffield, and Krebs was appointed as the Director. With this his laboratory became so expanded that the locals jokingly nicknamed it “Krebs's Empire”. He moved with his MRC unit to the University of Oxford in 1954 as Whitley Professor of Biochemistry, the post he held till his retirement in 1967. The editorial board of Biochemical Journal extended their good wishes on his retirement, but in return he promised to keep them busy (by producing scientific papers). He continued research and took his MRC unit to the Nuffield Department of Clinical Medicine at the Radcliffe Infirmary, Oxford. From there he published over 100 research papers.[10][11][16][17]

Personal life and death

Krebs met Margaret Cicely Fieldhouse (born 1913) when he moved to Sheffield in 1935. They married on 22 March 1938. Krebs later described his life in Sheffield as “19 happy years”.[10] They had two sons, Paul (born 1939) and John (born 1945), and a daughter, Helen (born 1942).[18] John (Sir John Krebs, and later Baron Krebs) became a renowned ornithologist, Professor at the University of Oxford, Principal of Jesus College, Oxford, and Member of the British House of Lords.[19]

After a brief illness, Krebs died on 22 November 1981 in Oxford.[3][20]


Krebs-Henseleit (urea) cycle

While working at the Medical Clinic of the University of Freiburg, Krebs met Kurt Henseleit, with whom he investigated the chemical process of urea formation. In 1904, two Germans A. Kossel and H.D. Dakin had shown that arginine could be hydrolysed by the enzyme arginase to form ornithine and urea in inorganic reaction.[21] Based on this reaction, Krebs and Henseleit postulated that in living cells, similar reaction could occur, and that ornithine and citrulline could be the intermediate reactions.[22][23] Krebs started working on the possible method for the synthesis of arginine. Using his Warburg manometer, he mixed a slice of liver with purified ornithine and citrulline. He found that citrulline acted as a catalyst in the metabolic reactions of urea from ammonia and carbon dioxide. He and Henseleit published their discovery in 1932. Thus the ornithine cycle was established, and it was the first metabolic cycle to be discovered.[15][24]

Krebs (TCA) cycle

At the University of Sheffield, Krebs and William Johnson investigated cellular respiration by which oxygen was consumed to produce energy from the breakdown of glucose. Krebs had earlier suggested to Warburg while they worked together in Germany that using manometer it could be possible to detect the oxygen consumption and identify the chemical reaction in glucose metabolism. Warburg had flatly rejected the idea. In Sheffield he vigorously worked for possible chemical reaction and came up with numerous hypothetical pathways. Using the manometer he tested those hypotheses one by one. One hypothesis involving succinate, fumarate, and malate proved to be useful because all these molecules increased oxygen consumption in the pigeon breast muscle. In 1937 German biochemists Franz Koop and Carl Martinus had demonstrated a series of reactions using citrate that produced oxaloacetate. Krebs realised his chemicals could be the missing intermediates for such reaction. After four months of experimental works to fill the gap, Krebs and Johnson succeeded in establishing the sequence of the chemical cycle, which they called the "citric acid cycle".[25][26]

Krebs sent a short manuscript account of the discovery to Nature on 10 June 1937. On 14 June he received a rejection letter from the editor, saying that the journal had "already sufficient letters to fill correspondence columns for seven or eight weeks", and encouraging Krebs to "submit it for early publication to another periodical."[27] Krebs immediately prepared a longer version titled "The Role of Citric Acid in Intermediate Metabolism in Animal Tissues", which he sent to the Dutch journal Enzymologia after two weeks and was published in two months.[3][28] It was followed by a series of papers in different journals.[29][30][31]

Glyoxylate cycle

Krebs continued to add more details to his citric acid cycle. The discovery of acetyl-CoA in 1947 by Fritz Albert Lipmann was another major contribution.[4][32] However, this new discovery posed a problem in his classic reaction. In 1957 he, with Hans Kornberg, found that there were additional crucial enzymes. One was malate synthase, which condenses acetate with glyoxylate to form malate, and the other was isocitrate lyase, which provides glyoxylate for the reaction by cleaving it from isocitrate.[33] These two reactions did not follow the normal citric acid cycle, and hence the pathway was named the glyoxylate bypass of the citric acid cycle, but is now known as the glyoxylate cycle.[15][34]

Honours and awards

Krebs became a naturalised British citizen in 1939. He was elected Fellow of Trinity College, Oxford, 1954-1967. He was elected to the Royal Society in 1947. In 1953 he received the Nobel Prize in Physiology or Medicine for his "discovery of the citric acid cycle." (He shared the Nobel Prize with Fritz Lipmann.) For the same reason he was given the Albert Lasker Award for Basic Medical Research in 1953.[35] The Royal Society awarded him its Royal Medal in 1954, and Copley Medal in 1961.[19] In 1958 he received the Gold Medal of the Netherlands Society for Physics, Medical Science and Surgery. He was knighted in 1958 and was elected Honorary Fellow of Girton College, Cambridge University in 1979. He was the Original Member of the Society for General Microbiology, which conferred him Honorary Membership in 1980. He received an honorary doctorate from 21 universities.[36]


The University of Oxford had a building named Hans Krebs Tower, which was occupied by the Department of Biochemistry. In 2008 a new building for the Department of Biochemistry was constructed, on which a plaque was placed on 20 May 2013 by the Association of Jewish Refugees.[37] The plaque was unveiled by John, Lord Krebs, and the inscription reads:[38]

Professor Sir Hans Krebs FRS 1900 – 1981 Biochemist & discoverer of the Krebs cycle Nobel Prize Winner 1953 worked here 1954 – 1967

The University of Sheffield has The Krebs Institute, founded in 1988. It is a research centre covering interdisciplinary programmes in biochemical research.[39]

In 1990 the Federation of European Biochemical Societies instituted the Sir Hans Krebs Lecture and Medal, which was endowed by the Lord Rank Centre for Research. It is awarded for outstanding achievements in biochemistry and molecular biology.[40][41]

The Society of Friends of Hannover Medical School gives the Sir Hans Krebs Prize, which is worth 10,000 euros.[42][43]

The Biochemical Society offers Krebs Memorial Scholarship to a postgraduate (PhD) student working in biochemistry or an allied biomedical science at any British university. As of 2014, the scholarship is worth £18,500 and is given for a year, but is extendable up to three years.[44]

See also


  1. Kornberg, H.; Williamson, D. H. (1984). "Hans Adolf Krebs. 25 August 1900-22 November 1981". Biographical Memoirs of Fellows of the Royal Society. 30 (0): 350–385. doi:10.1098/rsbm.1984.0013.
  2. Weber, George (2001). "Sir Hans A. Krebs Centenary Lecture: cancer and clinical targeting". Advances in Enzyme Regulation. 41 (1): 1–29. doi:10.1016/S0065-2571(00)00026-1. PMID 11417529.
  3. 1 2 3 Gibbons, Marion Stubbs, Geoff (2000). "Hans Adolf Krebs (1900-1981)...His Life and Times". IUBMB Life (International Union of Biochemistry and Molecular Biology: Life). 50 (3): 163–166. doi:10.1080/152165400300001462.
  4. 1 2 Raju, Tonse NK (1999). "The Nobel Chronicles". The Lancet. 353 (9164): 1628. doi:10.1016/S0140-6736(05)75758-5. PMID 10334294.
  5. Kantha, S. Sri (1991). "The question of nepotism in the award of Nobel prizes: A critique of the view of Hans Krebs". Medical Hypotheses. 34 (1): 28–32. doi:10.1016/0306-9877(91)90061-3. PMID 2056924.
  6. "Sir Hans Adolf Krebs". Encyclopædia Britannica, Inc. Retrieved 26 July 2014.
  7. Leigh, F W (2009). "Sir Hans Adolf Krebs (1900-81), pioneer of modern medicine, architect of intermediary metabolism". Journal of Medical Biography. 17 (3): 149–154. doi:10.1258/jmb.2009.009032. PMID 19723965.
  8. Edsall, John T (1993). "Master of metabolic cycles". Nature. 366 (6454): 417–418. doi:10.1038/366417a0.
  9. Hans, Krebs; Martin, Anne (1981). Reminiscences and Reflections. Oxford: Clarendon Press. p. 14. ISBN 978-0-1985-4702-0.
  10. 1 2 3 Willcocks, Elizabeth. "A lucky man". Royal Society of Chemistry. Retrieved 28 July 2014.
  11. 1 2 Quayle, J. R. (1982). "Obituary". Microbiology. 128 (10): 2215–2220. doi:10.1099/00221287-128-10-2215. PMID 6759612.
  12. Bailey, Leslie E; Ong, Seok D (1978). "Krebs-Henseleit solution as a physiological buffer in perfused and superfused preparations". Journal of Pharmacological Methods. 1 (2): 171–175. doi:10.1016/0160-5402(78)90022-0.
  13. "Krebs-Henseleit Buffer Modified". Sigma-Aldrich Co. LLC. Retrieved 28 July 2014.
  14. Hans, Krebs; Martin, Anne (1981). Reminiscences and Reflections. p. 48.
  15. 1 2 3 Wilson, B. A.; Schisler, J. C.; Willis, M. S. (2010). "Sir Hans Adolf Krebs: Architect of Metabolic Cycles". Laboratory Medicine. 41 (6): 377–380. doi:10.1309/LMZ5ZLAC85GFMGHU.
  16. Williamson, DH (1982). "Sir Hans Krebs (1900-1981)". The Biochemical Journal. 204 (1): 1–2. doi:10.1042/bj2040001. PMID 7052063.
  17. Williamson, DH (1981). "Tribute to Sir Hans Krebs". Biochemical Society Transactions. 9 (1): 1–2. doi:10.1042/bst0090001. PMID 7011867.
  18. "Lady Margaret Krebs". wickersleyweb.co.uk. Retrieved 29 July 2014.
  19. 1 2 "Hans Krebs". NNDB. Soylent Communications. Retrieved 31 July 2016.
  20. Altman, Lawrence K. (9 December 1981). "Sir Hans Krebs, winner of Nobel for research on food cycles, dies". The New York Times. Retrieved 13 December 2014.
  21. Kinne-Saffran, E; Kinne, RK (1999). "Vitalism and synthesis of urea. From Friedrich Wöhler to Hans A. Krebs". American Journal of Nephrology. 19 (2): 290–294. doi:10.1159/000013463. PMID 10213830.
  22. Graßhoff, Gerd; May, Michael (2003). "Hans Krebs' and Kurt Henseleit's Laboratory Notebooks and Their Discovery of the Urea Cycle-Reconstructed with Computer Models". In Holmes, Frederic L.; Renn, Jürgen; Rheinberger, Hans-Jörg. Reworking the Bench : Research Notebooks in the History of Science. Dordrecht: Kluwer Academic Publishers. pp. 269–294. doi:10.1007/0-306-48152-9_13. ISBN 978-1-4020-1039-2.
  23. Nickelsen, Kärin; Graßhoff, Gerd (2009). Hon, Giora; Schickore, Jutta; Steinle, Friedrich, eds. Going Amiss in Experimental Research. Dordrect, Netherlands: Springer Verlag. pp. 91–117. doi:10.1007/978-1-4020-8893-3_7. ISBN 978-1-4020-8892-6.
  24. Holmes, FL (1980). "Hans Krebs and the discovery of the ornithine cycle". Federation Proceedings. 39 (2): 216–25. PMID 6986292.
  25. Krebs, HA; Johnson, WA (1937). "Metabolism of ketonic acids in animal tissues.". The Biochemical Journal. 31 (4): 645–60. doi:10.1042/bj0310645. PMC 1266984Freely accessible. PMID 16746382.
  26. Krebs, HA; Johnson, WA (1937). "Acetopyruvic acid (alphagamma-diketovaleric acid) as an intermediate metabolite in animal tissues". The Biochemical Journal. 31 (5): 772–9. doi:10.1042/bj0310772. PMC 1267003Freely accessible. PMID 16746397.
  27. Borrel, Brendan (1 March 2010). "Nature rejects Krebs's paper, 1937". The Scientist. Retrieved 29 July 2014.
  28. Lalchhandama, K (2012). "How to write a rather tenacious and legible scientific paper" (PDF). Science Vision. 12 (2): 41–54.
  29. Krebs, H.A. (1937). "THE INTERMEDIATE METABOLISM OF CARBOHYDRATES". The Lancet. 230 (5952): 736–738. doi:10.1016/S0140-6736(00)88690-0.
  30. Krebs, HA; Salvin, E; Johnson, WA (1938). "The formation of citric and alpha-ketoglutaric acids in the mammalian body". The Biochemical Journal. 32 (1): 113–7. doi:10.1042/bj0320113. PMC 1264001Freely accessible. PMID 16746585.
  31. Krebs, HA (1938). "Micro-determination of alpha-ketoglutaric acid". The Biochemical Journal. 32 (1): 108–12. doi:10.1042/bj0320108. PMC 1264000Freely accessible. PMID 16746584.
  32. Buchanan, JM (2002). "Biochemistry during the life and times of Hans Krebs and Fritz Lipmann". The Journal of Biological Chemistry. 277 (37): 33531–6. doi:10.1074/jbc.R200019200. PMID 12070179.
  33. Kornberg, HL; Krebs, HA (1957). "Synthesis of cell constituents from C2-units by a modified tricarboxylic acid cycle.\". Nature. 179 (4568): 988–91. doi:10.1038/179988a0. PMID 13430766.
  34. Kornberg, Hans (2000). "Krebs and his trinity of cycles". Nature Reviews Molecular Cell Biology. 1 (3): 225–228. doi:10.1038/35043073. PMID 11252898.
  35. "Albert Lasker Basic Medical Research Award". Lasker Foundation. Retrieved 29 July 2014.
  36. Kronberg, Hans. "Krebs, Sir Hans Adolf (1900–1981), biochemist". Oxford Dictionary of National Biography. Oxford University Press. Retrieved 28 July 2014.
  37. Shock, Kathy (2013). "New Blue Plaque in Oxford". Oxford Jewish Heritage. Retrieved 28 July 2014.
  38. Itzhaki, Jane (22 May 2013). "Plaque unveiled to honour work of Sir Hans Krebs". Department of Biochemistry, University of Oxford. Retrieved 28 July 2014.
  39. "About [The Krebs Institute]". The Krebs Institute. Retrieved 28 July 2014.
  40. "FEBS Medals". Federation of European Biochemical Societies. Retrieved 28 July 2014.
  41. "The Sir Hans Krebs Medal of the Federation of European Biochemical Societies". University of Dundee. Retrieved 28 July 2014.
  42. "Heineke receives the Sir Hans Krebs Prize". REBIRTH HANNOVER. 2 December 2011. Retrieved 29 July 2014.
  43. "Ivan Dikic is awarded the Sir Hans Krebs Prize for his research on ubiquitin". Boehringer Ingelheim Fonds. Retrieved 29 July 2014.
  44. "Krebs Memorial Scholarship". Biochemical Society. Retrieved 29 July 2014.


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