- Person
- Hans Krebs
- Lived
- 1900–1981
- Field
- Biochemistry
- From
- German-British
The story
Hans Krebs was born in 1900 in Hildesheim, Germany, to parents from Jewish families, and trained as a doctor and biochemist. In 1932, at the University of Freiburg, he and Kurt Henseleit discovered the urea cycle, the loop of reactions the liver uses to get rid of toxic nitrogen, the first metabolic cycle ever described. Months later the Nazis came to power, and in 1933 Krebs was dismissed under the law that removed Jews from public posts. Sir Frederick Gowland Hopkins brought him to Cambridge, and in 1935 he moved to the University of Sheffield.
There he tackled one of the great unsolved questions of biology: how do cells burn food for energy? Many individual reactions were known, but not how they fitted together. Working with his student William Arthur Johnson on minced pigeon breast muscle, Krebs found that small amounts of citric acid made the muscle use far more oxygen than the citric acid itself could account for. Combining this with recent work by Carl Martius and Franz Knoop, he assembled the whole pathway within weeks.
It was a cycle. Fragments of broken-down food join a carrier molecule to form citric acid, which is then stripped step by step of its energy, releasing carbon dioxide, until the carrier is regenerated to go round again. In June 1937 Krebs sent a short paper to Nature, which replied that it already had enough letters to fill its columns for seven or eight weeks. He published a fuller account in the Dutch journal Enzymologia instead.
The citric acid cycle, also called the Krebs cycle, turned out to be the central hub of metabolism, where the breakdown of sugars, fats and proteins converges. In 1953 Krebs shared the Nobel Prize in Physiology or Medicine with Fritz Lipmann, whose discovery of coenzyme A showed how fuel enters the cycle. Krebs later moved to Oxford and was knighted in 1958.
Why it matters
The Krebs cycle is the core of how the body makes energy from food, taught to every medical student and used to understand diabetes, inherited metabolic diseases and cancer metabolism.
About Hans Krebs
German-born biochemist, forced out by the Nazis in 1933, who discovered the urea cycle and the citric acid cycle by which every cell turns food into energy. Nobel Prize 1953.
Sources
- Hans Krebs, Biographical NobelPrize.org
- Krebs, Hans Adolf Encyclopedia.com (Complete Dictionary of Scientific Biography)
- Hans Krebs (biochemist) Wikipedia
Another act of tikkun olam. This is part of tikkun olam, the Jewish idea of repairing the world, and every one of us can add to it.