Editing Hans Krebs (biochemist)

{{Short description|British biochemist (1900–1981)}}
{{other people||Hans Krebs (disambiguation)}}
{{Use British English|date=July 2017}}
{{Use dmy dates|date=August 2022}}
{{Infobox scientist
| honorific_prefix = [[Sir]]
| honorific_suffix = [[Fellowship of the Royal Society|FRS]]
| name        = Hans Krebs
| image       = Hans Adolf Krebs.jpg
| image_size  = 
| birth_date  = {{birth date|df=yes|1900|8|25}}
| birth_place = [[Hildesheim]], [[Province of Hanover]], [[Kingdom of Prussia]], [[German Empire]]
| citizenship = [[Naturalised British citizen|Naturalised British]] (from 1939)
| death_date  = {{death date and age|df=yes|1981|11|22|1900|8|25}}
| death_place = [[Oxford]], [[England]], [[United Kingdom]]
| field       = [[Internal medicine]], [[biochemistry]]
| workplaces  = [[Kaiser Wilhelm Institute for Biology]]<br>[[University of Hamburg]]<br>[[University of Cambridge]]<br>[[University of Sheffield]]<br>[[University of Oxford]]
| education   = [[University of Göttingen]]<br>[[University of Freiburg]]<br>[[University of Berlin]]<br>[[University of Hamburg]]
| known_for   = [[Citric acid cycle]]<br>[[Urea cycle]]<br>[[Glyoxylate cycle]]<br>[[Krebs–Henseleit solution]]
| prizes      = [[Albert Lasker Award for Basic Medical Research]] (1953)<br>[[Nobel Prize in Physiology or Medicine]] (1953)<br>[[Royal Medal]] (1954)<br>[[Copley Medal]] (1961)
| spouse      = {{marriage|Margaret Cicely Fieldhouse|1938}}
| children = Paul, [[John Krebs, Baron Krebs|John]], and Helen
}}

'''Sir Hans Adolf Krebs''', [[Fellowship of the Royal Society|FRS]] ({{IPAc-en|k|r|ɛ|b|z|,_|k|r|ɛ|p|s}}, {{IPA|de|hans ˈʔaːdɔlf ˈkʁeːps|lang|De-Hans Adolf Krebs.ogg}}; 25 August 1900 – 22 November 1981)<ref>{{cite journal|last1=Kornberg|first1=H.|last2=Williamson|first2=D. H.|title=Hans Adolf Krebs. 25 August 1900 – 22 November 1981|journal=Biographical Memoirs of Fellows of the Royal Society|year=1984|volume=30|pages=350–385|doi=10.1098/rsbm.1984.0013|pmid=11616005|doi-access=free}}</ref><ref>{{cite journal|last1=Weber|first1=George|title=Sir Hans A. Krebs Centenary Lecture: cancer and clinical targeting|journal=Advances in Enzyme Regulation|year=2001|volume=41|issue=1|pages=1–29|doi=10.1016/S0065-2571(00)00026-1|pmid=11417529}}</ref><ref name=stubbs>{{cite journal|last1=Gibbons|first1=Marion Stubbs, Geoff|title=Hans Adolf Krebs (1900–1981)...His Life and Times|journal=IUBMB Life|year=2000|volume=50|issue=3|pages=163–166|doi=10.1080/152165400300001462|pmid=11142342|s2cid=26393428|doi-access=free}}</ref><ref name=raju>{{cite journal|last1=Raju|first1=Tonse NK|title=The Nobel Chronicles|journal=The Lancet|year=1999|volume=353|issue=9164|pages=1628|doi=10.1016/S0140-6736(05)75758-5|pmid=10334294|s2cid=54354255}}</ref> was a German-British [[biologist]], [[physician]] and [[biochemist]].<ref>{{cite web|title=Sir Hans Adolf Krebs|url=http://www.britannica.com/nobelprize/article-9046221?tocId=9046221|publisher=Encyclopædia Britannica, Inc.|access-date=26 July 2014}}</ref> He was a pioneer scientist in the study of [[cellular respiration]], a biochemical process in [[Cell (biology)|living cells]] that extracts energy from food and [[oxygen]] and makes it available to drive the processes of life.<ref>{{cite journal|last1=Leigh|first1=F W|title=Sir Hans Adolf Krebs (1900–81), pioneer of modern medicine, architect of intermediary metabolism|journal=Journal of Medical Biography|year=2009|volume=17|issue=3|pages=149–154|doi=10.1258/jmb.2009.009032|pmid=19723965|s2cid=207200346}}</ref><ref>{{cite journal|last1=Edsall|first1=John T|title=Master of metabolic cycles|journal=Nature|year=1993|volume=366|issue=6454|pages=417–418|doi=10.1038/366417a0|bibcode=1993Natur.366..417E|s2cid=4241345}}</ref> He is best known for his discoveries of two important sequences of chemical reactions that take place in the cells of nearly all [[organism]]s, including humans, other than anaerobic microorganisms, namely the [[citric acid cycle]] and the [[urea cycle]]. The former, often eponymously known as the "Krebs cycle", is the sequence of metabolic reactions that allows cells of [[Aerobic organism|oxygen-respiring organisms]] to obtain far more [[Adenosine triphosphate|ATP]] from the food they consume than anaerobic processes such as [[glycolysis]] can supply; and its discovery earned Krebs a [[Nobel Prize in Physiology or Medicine]] in 1953. With [[Hans Kornberg]], he also discovered the [[glyoxylate cycle]],<ref name = glyox /> a slight variation of the citric acid cycle found in plants, [[bacteria]], [[protists]], and fungi. 

Krebs died in 1981 in [[Oxford]], where he had spent 13 years of his career from 1954 until his retirement in 1967 at the [[University of Oxford]].

== Biography ==
=== Early life and education ===
Krebs was born in [[Hildesheim]], Germany, to Georg Krebs, an [[Otolaryngology|ear, nose, and throat]] surgeon, and Alma Krebs (née Davidson).<ref name="Nobel bio">{{cite web |title=The Nobel Prize in Physiology or Medicine 1953 |website=NobelPrize.org |year=1953 |url=https://www.nobelprize.org/prizes/medicine/1953/krebs/biographical/ |access-date=11 June 2024}}</ref> He was of [[Jews|Jewish]] ancestry and was the middle of three children.<ref name="Nicholls 2020">{{cite journal |last1=Nicholls |first1=Mark |title=Hans Krebs |journal=European Heart Journal |volume=41 |issue=35 |date=14 September 2020 |issn=0195-668X |doi=10.1093/eurheartj/ehaa604 |pages=3294–3296|pmid=33033838 }}</ref> He had an elder sister, Elisabeth, and a younger brother, Wolfgang.<ref name="Roth 2020">{{cite journal |last1=Roth |first1=Klaus |title=Sir Hans Adolf Krebs (1900 – 1981) – Part 1 |journal=ChemViews |date=3 November 2020 |doi=10.1002/chemv.202000103}}</ref>

Krebs attended school at the [[:de:Gymnasium Andreanum|Gymnasium Andreanum]] in his home town.<ref name="Nobel bio" /> Near the end of [[World War I]], in September 1918, six months short of completing his secondary school education, he was [[conscripted]] into the [[Imperial German Army]].<ref name="Nicholls 2020" /> He was allowed to take an emergency examination for his high school diploma, which he passed with such a high score that he suspected the examiners of being "unduly lenient and sympathetic".<ref>{{cite book|last1=Hans|first1=Krebs|last2=Martin|first2=Anne|title=Reminiscences and Reflections|year=1981|publisher=Clarendon Press|location=Oxford|isbn=978-0-1985-4702-0|page=14|url=https://books.google.com/books?id=27-4AAAAIAAJ}}</ref> With the end of the war two months later, his conscription ended.<ref name="Nicholls 2020" />

Krebs 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]].<ref name="Nobel bio" /> In 1923, he published his first scientific paper on a [[Histology|tissue staining technique]]. He did this work under the guidance of Wilhelm von Mollendorf starting it in 1920.<ref name="Roth 2020" /> He completed his medical course in December 1923. To obtain a [[Doctor of Medicine]] degree, and a medical license, he spent one year at the Third Medical Clinic in the [[University of Berlin]].<ref name="Nobel bio" /> By then he had turned his professional goal from becoming a practising physician to becoming a medical researcher, particularly in biochemistry. In 1924, he studied at the Department of Chemistry at the Pathological Institute of the [[Charité]] Hospital, in [[Berlin]], for training in chemistry and biochemistry.<ref name="Holmes 1991">{{cite book |last1=Holmes |first1=Frederic Lawrence |title=Hans Krebs |publisher=Oxford University Press |series=Monographs on the History and Philosophy of Biology |year=1991 |isbn=978-0-19-536128-5 |url=https://books.google.com/books?id=qi8qfnKTuGoC&pg=PA121 |access-date=12 June 2024 |page=121}}</ref> He earned his [[Doctor of Medicine|MD]] degree in 1925 from the [[University of Hamburg]].<ref name="Nicholls 2020" /><ref name=rsc>{{cite web|last1=Willcocks|first1=Elizabeth|title=A lucky man|url=http://www.rsc.org/chemistryworld/Issues/2003/June/luckyman.asp|publisher=Royal Society of Chemistry|date=1 June 2003}}</ref><ref name=quayle>{{cite journal|last1=Quayle|first1=J. R.|title=Obituary|journal=Microbiology|year=1982|volume=128|issue=10|pages=2215–2220|doi=10.1099/00221287-128-10-2215|pmid=6759612|doi-access=free}}</ref>

=== Career ===
In 1926, Krebs joined [[Otto Heinrich Warburg]] as a research assistant at the [[Kaiser Wilhelm Institute for Biology]] in [[Dahlem (Berlin)|Dahlem, Berlin]].<ref>{{cite book|editor=Richter, Dietmar|author=Krebs, Hans A.|author2=Lipmann, Fritz|author-link2=Fritz Albert Lipmann|title=Lipmann Symposium. Energy transformation in biological systems|pages=7–27|year=1974|location=Berlin|publisher=Walter De Gruyter|chapter=Dahlem in the Late Nineteen Twenties|isbn=9783112316269 |chapter-url=https://books.google.com/books?id=kaTiDwAAQBAJ&pg=PA7}}</ref> He was paid 4800 [[Mark (currency)|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, Hamburg|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 research student [[Kurt Henseleit]], published their discovery of the ornithine cycle of urea synthesis, which is the metabolic pathway for [[urea]] formation. It is now known as the [[urea cycle]], and is sometimes also referred to as the Krebs–Henseleit cycle. Together they also developed a complex [[aqueous solution]] (a [[Buffer solution|buffer]]), or [[perfusion]] ''ex vivo'', for studying blood flow in arteries, which is now called the Krebs–Henseleit buffer.)<ref>{{cite journal|last1=Bailey|first1=Leslie E|last2=Ong|first2=Seok D|title=Krebs–Henseleit solution as a physiological buffer in perfused and superfused preparations|journal=Journal of Pharmacological Methods|year=1978|volume=1|issue=2|pages=171–175|doi=10.1016/0160-5402(78)90022-0}}</ref><ref>{{cite web|title=Krebs–Henseleit Buffer Modified|url=http://www.sigmaaldrich.com/catalog/product/sigma/k3753?lang=en&region=IN|publisher=Sigma-Aldrich Co. LLC.|access-date=28 July 2014}}</ref> In 1932, he published the basic chemical reactions of the urea cycle, which established his scientific reputation.

Krebs's life as a respected German scientist came to an abrupt halt in 1933 because of his Jewish ancestry. With the rise of [[Adolf Hitler|Hitler]]'s [[Nazi Party]] to power, Germany decreed the [[Law for the Restoration of the Professional Civil Service]], which decreed the removal of all non-Germans, and anti-Nazis, from professional occupations. Krebs received his official dismissal from his job in April 1933, and his service was terminated on 1 July 1933. 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.<ref>{{cite book|last1=Hans|first1=Krebs|last2=Martin|first2=Anne|title=Reminiscences and Reflections|year=1981|publisher=Clarendon Press|location=Oxford|isbn=978-0-1985-4702-0|page=48|url=https://books.google.com/books?id=27-4AAAAIAAJ}}</ref> By July 1933, he was settled in Cambridge with financial support from the [[Rockefeller Foundation]]. 

Although Germany restricted him to bringing only his personal belongings, he was fortunate that the government agents allowed him to take his equipment and research samples to England. 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.<ref name=wilson>{{cite journal|last1=Wilson|first1=B. A.|last2=Schisler|first2=J. C.|last3=Willis|first3=M. S.|title=Sir Hans Adolf Krebs: Architect of Metabolic Cycles|journal=Laboratory Medicine|year=2010|volume=41|issue=6|pages=377–380|doi=10.1309/LMZ5ZLAC85GFMGHU|doi-access=free}}</ref> 

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. The 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 a Professor in 1945. During his time it became one of the leading departments of biochemistry in the world.<ref>Among the distinguished biochemists who worked at Sheffield during that period were [[Keith Dalziel]], [[Quentin Gibson]], [[Hans Kornberg]], [[Vincent Massey (enzymologist)|Vincent Massey]] and [[Gregorio Weber]]</ref> Krebs took over the running of the [[Sorby Research Institute]] in 1943. In 1944, the British [[Medical Research Council (United Kingdom)|Medical Research Council]] established the MRC Unit for Cell Metabolism Research at Sheffield, and Krebs was appointed the Director. With this, his laboratory became so large 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 until 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 his 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.<ref name=rsc/><ref name=quayle/><ref>{{cite journal|last1=Williamson|first1=DH|title=Sir Hans Krebs (1900–1981)|journal=[[The Biochemical Journal]]|year=1982|volume=204|issue=1|pages=1–2|pmid=7052063|doi=10.1042/bj2040001|pmc=1158308}}</ref><ref>{{cite journal|last1=Williamson|first1=DH|title=Tribute to Sir Hans Krebs|journal=[[Biochemical Society Transactions]]|year=1981|volume=9|issue=1|pages=1–2|pmid=7011867|doi=10.1042/bst0090001}}</ref>

==Personal life==
[[File:Hans Krebs with wife 1953.jpg|thumb|left|Krebs with his wife in Stockholm in 1953]]
Krebs met Margaret Cicely Fieldhouse (30 October 1913 – May 1993)<ref>{{Cite web | url=https://www.geni.com/people/Margaret-Krebs/6000000029297312586 | title=Margaret Cicely Krebs| date=22 June 2018}}</ref> when he moved to Sheffield in 1935. They married on 22 March 1938. Krebs later described his life in Sheffield as "19 happy years".<ref name=rsc/> They had two sons, Paul (born 1939) and John (born 1945), and a daughter, Helen (born 1942).<ref>{{cite web|title=Lady Margaret Krebs|url=http://www.wickersleyweb.co.uk/hist/krebs.htm|publisher=wickersleyweb.co.uk|access-date=29 July 2014|url-status=dead|archive-url=https://web.archive.org/web/20140809145137/http://www.wickersleyweb.co.uk/hist/krebs.htm|archive-date=9 August 2014}}</ref> John ([[John Krebs, Baron Krebs|Sir John Krebs, and later Baron Krebs]]) became a renowned [[ornithologist]], Professor at the University of Oxford, Principal of [[Jesus College, Oxford]], and [[British House of Lords|Member of the British House of Lords]].<ref>{{cite web |title=Lord Krebs {{!}} Jesus College, University of Oxford |url=http://www.jesus.ox.ac.uk/fellows-and-staff/fellows/lord-krebs |access-date=13 March 2024 |date=7 October 2011|archive-url=https://web.archive.org/web/20111007151631/http://www.jesus.ox.ac.uk/fellows-and-staff/fellows/lord-krebs |archive-date=7 October 2011 }}</ref>

==Death==
After a brief illness, Krebs died on 22 November 1981 in Oxford, aged 81.<ref name=stubbs/><ref>{{cite news|last1=Altman|first1=Lawrence K.|title=Sir Hans Krebs, winner of Nobel for research on food cycles, dies|url=https://www.nytimes.com/1981/12/09/obituaries/sir-hans-krebs-winner-of-nobel-for-research-on-food-cycles-dies.html|access-date=13 December 2014|work=The New York Times|date=9 December 1981}}</ref>

== Achievements ==

=== Urea cycle (Krebs–Henseleit cycle) ===
In 1932, Krebs worked out the outlines of the urea cycle with a medical student Kurt Henseleit at the [[University of Freiburg]]. 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.<ref>{{cite journal|last1=Kinne-Saffran|first1=E|last2=Kinne|first2=RK|title=Vitalism and synthesis of urea. From Friedrich Wöhler to Hans A. Krebs|journal=American Journal of Nephrology|year=1999|volume=19|issue=2|pages=290–294|pmid=10213830|doi=10.1159/000013463|s2cid=71727190}}</ref> 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.<ref>{{cite book|last1=Graßhoff|first1=Gerd|last2=May|first2=Michael|editor1-last=Holmes|editor1-first=Frederic L.|editor2-last=Renn|editor2-first=Jürgen|editor3-last=Rheinberger|editor3-link=Hans-Jörg Rheinberger|editor3-first=Hans-Jörg|title=Reworking the Bench : Research Notebooks in the History of Science|year=2003|publisher=Kluwer Academic Publishers|location=Dordrecht|isbn=978-1-4020-1039-2|pages=269–294|doi=10.1007/0-306-48152-9_13|chapter=Hans Krebs' and Kurt Henseleit's Laboratory Notebooks and Their Discovery of the Urea Cycle-Reconstructed with Computer Models}}</ref><ref>{{cite book|last1=Nickelsen|first1=Kärin|author1-link= Kärin Nickelsen |last2=Graßhoff|first2=Gerd|editor1-last=Hon|editor1-first=Giora|editor2-last=Schickore|editor2-first=Jutta|editor3-last=Steinle|editor3-first=Friedrich|title=Going Amiss in Experimental Research|year=2009|publisher=Springer Verlag|location=Dordrect, Netherlands|isbn=978-1-4020-8892-6|pages=91–117|doi=10.1007/978-1-4020-8893-3_7}}</ref> 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 [[urea cycle]] (or "ornithine cycle") was established, and it was the first metabolic cycle to be discovered.<ref name=wilson/><ref>{{cite journal|last1=Holmes|first1=FL|title=Hans Krebs and the discovery of the ornithine cycle|journal=Federation Proceedings|year=1980|volume=39|issue=2|pages=216–25|pmid=6986292}}</ref>

=== Citric acid cycle (Krebs cycle) ===
At the [[University of Sheffield]], Krebs and [[William Arthur Johnson (biochemist)|William Arthur Johnson]] investigated [[cellular respiration]] by which [[Allotropes of oxygen|oxygen]] was consumed to produce energy from the breakdown of [[glucose]]. Krebs had earlier suggested to Warburg while they worked together in Germany that by using a [[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, Krebs vigorously worked to identify a 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 Knoop]] and Carl Martinus had demonstrated a series of reactions using [[citrate]] that produced [[oxaloacetate]]. Krebs realised that these molecules could be the missing intermediates for such reaction. After four months of experimental works to fill in the gaps, Krebs and Johnson succeeded in establishing the sequence of the chemical cycle, which they called the "[[citric acid cycle]]".<ref>{{cite journal|last1=Krebs|first1=HA|last2=Johnson|first2=WA|title=Metabolism of ketonic acids in animal tissues.|journal=The Biochemical Journal|year=1937|volume=31|issue=4|pages=645–60|pmid=16746382|pmc=1266984|doi=10.1042/bj0310645}}</ref><ref>{{cite journal|last1=Krebs|first1=HA|last2=Johnson|first2=WA|title=Acetopyruvic acid (alphagamma-diketovaleric acid) as an intermediate metabolite in animal tissues|journal=The Biochemical Journal|year=1937|volume=31|issue=5|pages=772–9|pmid=16746397|pmc=1267003|doi=10.1042/bj0310772}}</ref> It is also known as the "Krebs cycle" or "[[tricarboxylic acid]] (TCA) cycle".

Krebs sent a short manuscript account of the discovery to ''[[Nature (journal)|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."<ref>{{cite journal|last1=Borrel|first1=Brendan|title=Nature rejects Krebs's paper, 1937|journal=The Scientist|date=1 March 2010|url=http://www.the-scientist.com/?articles.view/articleNo/28819/title/Nature-rejects-Krebs-s-paper--1937/|access-date=29 July 2014}}</ref> 

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.<ref name=stubbs/><ref>{{cite journal|last1=Lalchhandama|first1=K|title=How to write a rather tenacious and legible scientific paper|journal=Science Vision|year=2012|volume=12|issue=2|pages=41–54|url=http://www.sciencevision.org/current_issue/dl/Lalchhandama.pdf|url-status=dead|archive-url=https://web.archive.org/web/20140427025145/http://www.sciencevision.org/current_issue/dl/Lalchhandama.pdf|archive-date=27 April 2014}}</ref> It was followed by a series of papers in different journals.<ref>{{cite journal|last1=Krebs|first1=H.A.|title=The Intermediate Metabolism of Carbohydrates|journal=The Lancet|year=1937|volume=230|issue=5952|pages=736–738|doi=10.1016/S0140-6736(00)88690-0}}</ref><ref>{{cite journal|last1=Krebs|first1=HA|last2=Salvin|first2=E|last3=Johnson|first3=WA|title=The formation of citric and alpha-ketoglutaric acids in the mammalian body|journal=The Biochemical Journal|year=1938|volume=32|issue=1|pages=113–7|pmid=16746585|pmc=1264001|doi=10.1042/bj0320113}}</ref><ref>{{cite journal|last1=Krebs|first1=HA|title=Micro-determination of alpha-ketoglutaric acid|journal=The Biochemical Journal|year=1938|volume=32|issue=1|pages=108–12|pmid=16746584|pmc=1264000|doi=10.1042/bj0320108}}</ref>

=== 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.<ref name=raju/><ref>{{cite journal|last1=Buchanan|first1=JM|title=Biochemistry during the life and times of Hans Krebs and Fritz Lipmann|journal=The Journal of Biological Chemistry|year=2002|volume=277|issue=37|pages=33531–6|pmid=12070179|doi=10.1074/jbc.R200019200|doi-access=free}}</ref> 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.<ref name = glyox>{{cite journal|last1=Kornberg|first1=HL|last2=Krebs|first2=HA|title=Synthesis of cell constituents from C<sub>2</sub>-units by a modified tricarboxylic acid cycle|journal=Nature|year=1957|volume=179|issue=4568|pages=988–91|pmid=13430766|doi=10.1038/179988a0|bibcode=1957Natur.179..988K|s2cid=40858130}}</ref> 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]].<ref name=wilson/><ref>{{cite journal|last1=Kornberg|first1=Hans|title=Krebs and his trinity of cycles|journal=Nature Reviews Molecular Cell Biology|year=2000|volume=1|issue=3|pages=225–228|doi=10.1038/35043073|pmid=11252898|s2cid=28092593}}</ref>

== Honours and awards ==
[[File:Lady Churchill, Hans Krebs, Frits Zernike 1953.jpg|thumb|upright=1.1|Krebs with [[Clementine Churchill]] and [[Frits Zernike]] in Stockholm in 1953]]
Krebs became a [[naturalised British citizen]] in 1939. He was elected Fellow of [[Trinity College, Oxford|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.<ref>{{cite web|title=Albert Lasker Basic Medical Research Award|url=http://www.laskerfoundation.org/awards/1953basic.htm|publisher=Lasker Foundation|access-date=29 July 2014|url-status=dead|archive-url=https://web.archive.org/web/20141014000229/http://www.laskerfoundation.org/awards/1953basic.htm|archive-date=14 October 2014}}</ref> 

The Royal Society awarded him its [[Royal Medal]] in 1954, and [[Copley Medal]] in 1961.<ref>[https://www.leopoldina.org/fileadmin/redaktion/Mitglieder/CV_Krebs_Hans_D.pdf Hans Krebs' CV], Leopoldina.org. Accessed 8 February 2023.</ref> He was elected to the [[American Academy of Arts and Sciences]] in 1957.<ref>{{Cite web |title=Hans Adolf Krebs |url=https://www.amacad.org/person/hans-adolf-krebs |access-date=29 November 2022|website=American Academy of Arts & Sciences |language=en}}</ref> 

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 was also an elected member of both the [[American Philosophical Society]] and the United States [[National Academy of Sciences]].<ref>{{Cite web |title=APS Member History |url=https://search.amphilsoc.org/memhist/search?creator=Hans+Krebs&title=&subject=&subdiv=&mem=&year=&year-max=&dead=&keyword=&smode=advanced |access-date=29 November 2022|website=search.amphilsoc.org}}</ref><ref>{{Cite web |title=Hans Krebs |url=http://www.nasonline.org/member-directory/deceased-members/20001329.html |access-date=2022-11-29 |website=www.nasonline.org}}</ref> He received an honorary doctorate from 21 universities.<ref>{{cite ODNB|last1=Kronberg|first1=Hans|title=Krebs, Sir Hans Adolf (1900–1981), biochemist|volume=1|doi=10.1093/ref:odnb/31327|year=2004}}</ref>

In July 2015, Krebs's Nobel Prize medal was auctioned off for £225,000 (around $351,225).<ref>{{cite web|url=https://www.bbc.com/news/uk-england-south-yorkshire-33522526|title=Sheffield academic's Nobel Prize medal sells for £225,000|publisher=BBC|date=14 July 2015}}</ref><ref>{{cite web|url=http://www.the-scientist.com/?articles.view/articleNo/43521/title/Krebs-Nobel-Auctioned|title=Krebs Nobel Auctioned|website=TheScientist|date=16 July 2015|author=Keener, Amanda B. }}</ref> The proceeds were used to found the Sir Hans Krebs Trust, which provides funding for doctoral students in the biomedical field and support chemists who had to flee their home countries.<ref>{{Cite web |url=https://www.cara.ngo/sir-hans-krebs-trust-cara-fellowships/ |title=Sir Hans Krebs Trust / Cara Fellowships |date=1 December 2015 |website=Cara |access-date=19 November 2019 }}</ref>

== Legacy ==

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]].<ref>{{cite web|last1=Shock|first1=Kathy|title=New Blue Plaque in Oxford|url=http://www.oxfordjewishheritage.co.uk/news-a-events/news/221-new-blue-plaque-in-oxford|publisher=Oxford Jewish Heritage|access-date=28 July 2014|year=2013|archive-date=9 August 2014|archive-url=https://web.archive.org/web/20140809125740/http://www.oxfordjewishheritage.co.uk/news-a-events/news/221-new-blue-plaque-in-oxford|url-status=dead}}</ref> The plaque was unveiled by John, Lord Krebs, and the inscription reads:<ref>{{cite web|last1=Itzhaki|first1=Jane|title=Plaque unveiled to honour work of Sir Hans Krebs|url=http://www.bioch.ox.ac.uk/aspsite/index.asp?pageid=981|publisher=Department of Biochemistry, University of Oxford|access-date=28 July 2014|date=22 May 2013|archive-date=12 August 2014|archive-url=https://web.archive.org/web/20140812215942/http://www.bioch.ox.ac.uk/aspsite/index.asp?pageid=981|url-status=dead}}</ref>

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

The Department of Physiology, Anatomy and Genetics at Oxford University hosts the Sir Hans Krebs Prize Lecture Series.<ref>{{cite web|title=Sir Hans Krebs Prize Lecture Series|url=https://www.dpag.ox.ac.uk/named-lectures/hans-krebs-lecture}}</ref>
The last three recipients have been: Jeffrey Friedman M.D., PhD (2019) Professor Sir Stephen O'Rahilly MD FRS FMedSci (2022) and in 2023 - Professor Dame Frances Ashcroft FRS FMedSci <ref>{{cite web|title=About []Sir Hans Krebs Prize Lecture Series|url=https://www.dpag.ox.ac.uk/named-lectures/hans-krebs-lecture}}</ref>

The University of Sheffield has The Krebs Institute, founded in 1988. It is a research centre covering interdisciplinary programmes in biochemical research.<ref>{{cite web|title=About [The Krebs Institute]|url=http://www.krebs.group.shef.ac.uk/AboutKI.html|publisher=The Krebs Institute|access-date=28 July 2014|archive-date=10 May 2015|archive-url=https://web.archive.org/web/20150510025821/http://www.krebs.group.shef.ac.uk/AboutKI.html|url-status=dead}}</ref>

In 1990, the [[Federation of European Biochemical Societies]] instituted the [[Sir Hans Krebs Medal|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.<ref>{{cite web|title=FEBS Medals|url=http://www.febs.org/our-activities/awards/medals|publisher=Federation of European Biochemical Societies|access-date=28 July 2014}}</ref><ref>{{cite web|title=The Sir Hans Krebs Medal of the Federation of European Biochemical Societies|url=http://www.lifesci.dundee.ac.uk/awards/sir-hans-krebs-medal-federation-european-biochemical-societies|publisher=University of Dundee|access-date=28 July 2014|date=20 August 2013}}</ref>

The Society of Friends of [[Hannover Medical School]] gives the Sir Hans Krebs Prize, which is worth 10,000 euros.<ref>{{cite web|title=Heineke receives the Sir Hans Krebs Prize|url=http://www.rebirth-hannover.de/en/press-media/press-releases/singleview.html?tx_ttnews[year]=2011&tx_ttnews[month]=11&tx_ttnews[day]=02&tx_ttnews[tt_news]=27&cHash=1213fd16c777c3bd44dfc17c2d8dc36e|publisher=Rebirth Hannover|access-date=29 July 2014|date=2 December 2011}}{{Dead link|date=July 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref>{{cite web|title=Ivan Dikic is awarded the Sir Hans Krebs Prize for his research on ubiquitin|url=http://www.bifonds.de/news-network/news-pictures/news-item/items/ivan-dikic-is-awarded-the-sir-hans-krebs-prize-for-his-research-on-ubiquitin.html|publisher=Boehringer Ingelheim Fonds|date=13 November 2009|access-date=29 July 2014|archive-date=20 July 2018|archive-url=https://web.archive.org/web/20180720140005/https://www.bifonds.de/news-network/news-pictures/news-item/items/ivan-dikic-is-awarded-the-sir-hans-krebs-prize-for-his-research-on-ubiquitin.html|url-status=dead}}</ref>

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.<ref>{{cite web|title=Krebs Memorial Scholarship|url=http://www.biochemistry.org/Grants/KrebsMemorialScholarship.aspx|publisher=Biochemical Society|access-date=29 July 2014|archive-date=29 July 2014|archive-url=https://web.archive.org/web/20140729165412/http://www.biochemistry.org/Grants/KrebsMemorialScholarship.aspx|url-status=dead}}</ref>

==See also==
*[[List of Jewish Nobel laureates]]
*[[List of refugees]]

==References==
{{reflist|30em}}

==Bibliography==
*{{cite book |author1=Medawar, Jean |author2=Pyke, David | title = Hitler's Gift: The True Story of the Scientists Expelled by the Nazi Regime | location = New York | publisher = Arcade Publishing | year = 2012 | type = Paperback | isbn = 978-1-61145-709-4}}
*{{cite book|last1=Oakes|first1=Elizabeth H|title=Encyclopedia of World Scientists|date=2007|publisher=Facts on File|location=New York|isbn=978-1-4381-1882-6|page=414|edition=Rev.|url=https://books.google.com/books?id=uPRB-OED1bcC}}
*{{cite book|last1=Holmes|first1=Frederic Lawrence|title=Hans Krebs : Volume 1: The Formation of a Scientific Life, 1900–1933|date=1991|publisher=Oxford University Press|location=New York|isbn=978-0-195-07072-9|pages=512|url=https://books.google.com/books?id=qi8qfnKTuGoC}}

==External links==
*{{Nobelprize}} including the Nobel Lecture, 11 December 1953 ''The Citric Acid Cycle''
*[http://nobelprize.org/nobel_prizes/medicine/laureates/1953/ 1953 Prize in Physiology or Medicine] Nobel Prizes
*[http://www.deconstructingthetour.group.shef.ac.uk/krebs-cycle/ Deconstructing the Tour, University of Sheffield (biography)] {{Webarchive|url=https://web.archive.org/web/20210419085915/http://www.deconstructingthetour.group.shef.ac.uk/krebs-cycle/ |date=19 April 2021 }}
*[http://www.whonamedit.com/doctor.cfm/1541.html Sir Hans Adolf Krebs at whonamedit]
*[http://apps.nationalarchives.gov.uk/a2a/records.aspx?cat=200-csac113486_3&cid=0#0 Catalogue of the papers and correspondence of Sir Hans Adolf Krebs, FRS (1900–1981)]
* [https://nobel.bh.org.il/en/persona/Hans-Krebs/ Hans A. Krebs], Nobel Luminaries – Jewish Nobel Prize Winners, on the [https://www.bh.org.il/ Beit Hatfutsot-The Museum of the Jewish People] Website.

{{Copley Medallists 1951-2000}}
{{Nobel Prize in Physiology or Medicine Laureates 1951-1975}}
{{1953 Nobel Prize winners}}
{{Authority control}}

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[[Category:1900 births]]
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[[Category:Nobel laureates in Physiology or Medicine]]
[[Category:British Nobel laureates]]
[[Category:German Nobel laureates]]
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