- Person
- Otto Warburg
- Lived
- 1883–1970
- Field
- Biochemistry
- From
- German
The story
By the mid-1920s Otto Warburg was convinced that cells breathe with the help of an iron-containing enzyme, which he called the Atmungsferment, or respiratory enzyme. The difficulty was that it exists in cells in vanishingly small amounts, far too little to isolate with the tools of the time. He needed a way to study it while it was still working inside living cells.
His starting point was carbon monoxide. Claude Bernard had shown long before that the gas binds to haemoglobin, and in 1926, working with yeast cells suspended in a glucose solution, Warburg found that it also blocks cell respiration. The strength of the block depended on the ratio of carbon monoxide to oxygen, which told him that the gas was competing with oxygen for iron in the enzyme.
Then came the decisive step. The chemists Mond and Langer had discovered in 1891 that compounds of carbon monoxide and iron can be split apart by light. Warburg found that by alternating light and darkness he could make respiration in the poisoned cells appear and disappear: in the light, carbon monoxide was knocked off the iron, freeing the enzyme to work again. His measurements showed that the effect obeyed Einstein's law of photochemical equivalence, with one iron and carbon monoxide pair split for each quantum of light absorbed.
By shining light of different colours but equal intensity on the cells and recording how much respiration recovered, Warburg mapped the absorption spectrum of the enzyme without ever purifying it. The pattern closely resembled that of carbon monoxide bound to haemoglobin, shifted slightly toward longer wavelengths, which identified the enzyme as a haem compound. Its very strong light absorption also showed that it was present in the cell only in minute concentrations. This work, carried out between 1927 and 1932, formed the core of the discovery honoured by his 1931 Nobel Prize.
The method was an elegant piece of experimental reasoning, in which an invisible molecule was identified by the way it responded to light. Warburg himself regarded the discovery of the respiratory enzyme as the most original of his career. Reading the chemistry of molecules inside living cells through their interaction with light later became one of the standard approaches of biochemistry.
Why it matters
Warburg's approach showed scientists how to study molecules inside living cells by their response to light, an idea that runs through modern spectroscopy and biochemistry.
About Otto Warburg
Biochemist who uncovered how cells breathe and discovered that tumours burn sugar by fermentation, the “Warburg effect”; Nobel laureate in 1931 who kept working in Nazi Berlin as a “Mischling.”
More about Otto Warburg
- Otto Warburg found that cancer cells crave sugarBeginning in 1922, Otto Warburg discovered that tumour cells break down glucose into lactic acid even when oxygen is plentiful, a hallmark of cancer now called the Warburg effect.
- Otto Warburg's discovery lets PET scans find tumoursPET scans locate cancers by tracking a radioactive form of glucose that tumours absorb in excess, putting Otto Warburg's century-old discovery to work in hospitals every day.
- Otto Warburg built the tools of modern biochemistryOtto Warburg introduced the thin tissue-slice technique in 1923 and refined manometric methods for measuring how living tissue consumes oxygen, tools used in labs for decades.
- Otto Warburg discovered how cells use oxygenOtto Warburg identified the iron-containing enzyme that lets living cells use oxygen, winning the unshared 1931 Nobel Prize in Physiology or Medicine.
- Otto Warburg measured life's first breath in an eggWorking at the Naples marine station before the First World War, Otto Warburg showed that a sea urchin egg's respiration rises sharply the moment it is fertilised.
- Otto Warburg revealed the helper molecules of metabolismIn the 1930s Otto Warburg discovered the yellow enzymes and identified flavin and nicotinamide as the active parts of the enzymes that move hydrogen in living cells.
Sources
- Warburg, Otto Heinrich, Complete Dictionary of Scientific Biography Encyclopedia.com
- Otto Heinrich Warburg 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.