The Nobel Prize in Physiology or Medicine 1931.
"for his discovery of the nature and mode of action of the respiratory enzyme"
Otto Heinrich Warburg (1883 - 1970 ) received the Nobel Prize in Physiology or Medicine for his contributions to understanding cellular respiration. At the time he received the Nobel Prize, he was credited with discovering the "respiratory enzyme" and demonstrating that it required iron. The idea was that oxygen binds to iron during respiration in the same way that it binds to iron in hemoglobin. Here's how the discovery was described in the presentation speech on the Nobelprize.org website.
Definite proof that he was on the track of this well-hidden secret of Nature was obtained by the use of exact measurements of combustion in living cells or, as Warburg calls it, cell respiration. The quantitatively measured variations in the process of combustion under different conditions threw light on the nature of the respiratory ferment. Its tendency to enter into compounds with substances which combine with iron showed that it is itself an iron compound, and that its effects are due to iron.We now know that this is incorrect. Warburg probably worked with cytochrome c which has a iron-containing heme group [Monday's Molecule #88] but cytochrome c does not bind oxygen. It is an intermediate in the oxidation-reduction pathway, contributing electrons to cytochrome c oxidase—the real oxygen binding enzyme. Cytochrome c oxidase does have an iron heme group that contributes to oxygen binding but copper atoms are also intimately involved.
This is a case where the Nobel Prize was awarded to the right person for the wrong reasons. Warburg made lots of contributions to biochemistry. He discovered flavin proteins and did seminal work on oxidation-reduction enzymes that use NAD+ as a cofactor. He also contributed significantly to our understanding of photosynthesis.
Many people believe that Warburg received a second Nobel Prize in 1944 for these other contributions but he was unable to accept it because Hitler declared that Germans, especially Jewish Germans, could not accept a foreign prize. The Nobel Committee has repeatedly declared that Warbug was not offered the prize in 1944 although he was considered a strong candidate. This declaration has not squelched the myth of two Nobel Prizes—a myth that is largely propagated on cancer websites (e.g., stopcancer.com). Warburg claimed that cancer was caused when cells switched from aerobic glycolysis to fermentation and this has made him a hero among the pseudoscience crowd. That's a tremendous disservice to one of the greatest biochemists who ever lived.