Heritage · Legacy
Hans Adolf Krebs Legacy
German-British biochemist who discovered the urea cycle (1932) and the citric acid cycle (1937), sharing the 1953 Nobel Prize in Physiology or Medicine.Written to last — not to trend.
By Confinity Heritage Editorial · Updated 2026-07-31 · 6-minute readQuiet tools, not a toolbar.
Sir Hans Adolf Krebs was a German-British biochemist whose experiments mapped how living cells convert food into usable energy. Between 1932 and 1937 he described two of the central pathways of metabolism, the urea cycle and the citric acid cycle, and the second now carries his name. He shared the 1953 Nobel Prize in Physiology or Medicine with Fritz Lipmann. His forced departure from Nazi Germany in 1933 also became one of the plainest cases of British science gaining from what Germany discarded.
Krebs was born on 25 August 1900 in Hildesheim, then part of the Prussian province of Hanover. His father, Georg Krebs, was an ear, nose, and throat surgeon; his mother was Alma Krebs, born Davidson. Hans grew up with an elder sister, Elisabeth, and a younger brother, Wolfgang, and attended the Gymnasium Andreanum in his home town. He was briefly conscripted into the German army in the final months of the First World War before the fighting ended.
He entered the University of Göttingen in December 1918 to study medicine, following his father into the profession, and continued his training at Freiburg and Berlin. Krebs took his M.D. at the University of Hamburg in 1925, having already published his first paper, on a tissue-staining method, in 1923. Rather than settle into clinical practice, he moved toward laboratory research. From 1926 to 1930 he worked in Berlin under Otto Warburg at the Kaiser Wilhelm Institute for Biology, where he learned the exacting manometric methods that shaped everything he did afterward.
After leaving Warburg's laboratory, Krebs returned to hospital and research posts in Germany. In 1932, at the University of Freiburg, he and the medical student Kurt Henseleit worked out the urea cycle, the sequence by which the liver turns toxic ammonia into urea for excretion. It was the first metabolic cycle ever described, and it marked Krebs as a leading figure in the young study of intermediary metabolism.
His German career ended abruptly. In April 1933 the Nazi regime removed him from his post because of his Jewish ancestry, and by that summer he had emigrated to Britain to join Frederick Gowland Hopkins at the University of Cambridge. In 1935 he moved to the University of Sheffield as a lecturer in pharmacology. There, in 1937, he assembled the citric acid cycle, the closed loop of reactions that oxidises the breakdown products of sugar, fat, and protein to release energy. The pathway sits at the centre of aerobic respiration and supplies much of the energy used by higher organisms.
The discovery nearly went unread. Krebs and his student William Arthur Johnson submitted their report to the journal Nature, which declined it, citing a backlog of letters; the paper appeared instead in the Dutch journal Enzymologia later that year, according to contemporary accounts. The rejection did nothing to slow the work's acceptance, and the pathway is now taught worldwide as the Krebs cycle.
In 1953 Krebs shared the Nobel Prize in Physiology or Medicine with Fritz Lipmann, whose discovery of coenzyme A had explained how the two-carbon fragments entering the cycle are activated. He had already moved to the University of Oxford in 1954 as Whitley Professor of Biochemistry, a post he held until his retirement in 1967. Krebs was knighted in 1958 for his services to science and kept publishing long after leaving his chair.
His contributions did not stop with the two cycles. In 1957, with Hans Kornberg, he described the glyoxylate cycle, a variant of the citric acid cycle found in plants, bacteria, and fungi. The University of Sheffield opened the Krebs Institute for biomolecular research in 1988 in his memory, and his son John Krebs became a distinguished zoologist and public figure in his own right. Because the citric acid cycle underlies research on cancer, metabolic disease, and cell biology, Krebs's name remains in daily use in laboratories that never knew him.
Krebs's life joins two stories that are easy to keep apart: a scientific achievement and a human displacement. The citric acid cycle is among the most reproduced diagrams in biology, yet the man who first drew it was a refugee whom his own country expelled at the height of his powers. Confinity keeps his record so that the science and the person stay attached. A legacy page here holds the verified dates, the institutions, and the turning points in one place, so that anyone tracing how modern biochemistry took shape can find the evidence rather than the legend.
Early life
The citric acid cycle
Legacy
Why Confinity keeps Hans
References
Timeline
- 1900Born in Hildesheim, in the Prussian province of Hanover
- 1925Earns his M.D. at the University of Hamburg
- 1932Works out the urea cycle with Kurt Henseleit at Freiburg
- 1933Dismissed under Nazi law and emigrates to Britain
- 1937Describes the citric acid cycle at the University of Sheffield
- 1953Shares the Nobel Prize in Physiology or Medicine with Fritz Lipmann
- 1958Knighted for services to science