|A.K.A.||Hans Karl August Simon von Euler-Chelpin|
|Occupations||Biochemist Chemist University teacher Military personnel|
|Birth||15 February 1873 (Augsburg)|
|Death||6 November 1964 (Stockholm)|
|Education||Humboldt University of Berlin|
Hans Karl August Simon von Euler-Chelpin (15 February 1873 – 6 November 1964) was a German-born Swedish biochemist. He won the Nobel Prize in Chemistry in 1929 with Arthur Harden for their investigations on the fermentation of sugar and enzymes. He was a professor of general and organic chemistry at Stockholm University (1906–1941) and the director of its Institute for organic-chemical research (1938–1948). Euler-Chelpin married Astrid Cleve, the daughter of the Uppsala chemist Per Teodor Cleve and was the great-great-great grandson of Leonhard Euler. In 1970, his son Ulf von Euler, was awarded the Nobel Prize in Physiology or Medicine.
Euler-Chelpin was born on 15 February 1873 at Augsburg, Germany. His father was a captain in the Royal Bavarian Regiment, who was soon transferred to Munich. During his childhood, he spent most of his time with his grandmother at Wasserburg am Inn. He went to the Royal Junior High School in Augsburg (predecessor of Holbein Gymnasium ), also in Würzburg and Ulm. After serving as a one-year volunteer in the Bavarian first Field Artillery Regiment, he took interest in the color theory and began studying art at the Munich Academy of Painting (1891-1893). He was taught under Schmid-Reutte and Lenbach, a German painter of realist style. He therefore went to attend the University of Berlin to study chemistry under Emil Fischer and A. Rosenheim, and physics under E. Warburg and Max Planck; where in 1895 he received his doctorate.
In 1899 Euler-Chelpin was appointed to teach Privatdozent in the Royal University at Stockholm where he began visiting the laboratory of van 't Hoff, one of the many who influenced Euler-Chelpin's interest in science along with Nernst.
In 1902 he took Swedish citizenship. Nevertheless, during the First World War, Euler-Chelpin took part in voluntary service in the German Air Force.   During the Second World War, the professor worked in a diplomatic mission on the German side.
In 1906 he was appointed Professor of General and Organic Chemistry in the Royal University, Stockholm. In 1929, the Knut and Alice Wallenberg Foundation and the International Education Board of the Rockefeller Foundation established in Stockholm the Vitamin Institute and Institute of Biochemistry, and Euler-Chelpin was appointed as its director. In 1941 he retired from teaching, but continued his researches.
Hans von Euler-Chelpin married twice. His first wife was Astrid Cleve, who was the first Swedish woman to obtain a doctoral degree of science. In 1913 he married again to his second wife, Elisabeth Baroness af Ugglas (1887-1973), whose participated in collaborations with Euler-Chelpin. His son, Ulf von Euler (1905 - 1983), was a well-known physiologist and in 1970 he received a Nobel Prize for his research on the chemical nature of nor epinephrine on the synapses. In 1931, his daughter Karin von Euler-Chelpin married the writer Sven Stolpe.
During his life, Euler-Chelpin created a series of monographs such as Biochemistry of Tumours, written in collaboration with Boleslaw Skarzynski, published in 1942 and the other entitled The Chemotherapy and Prophylaxis of Cancer, published in 1962.
Euler-Chelpin died in Stockholm on 6 November 1964, at the age of 91.
In 1929, Euler-Chelpin and Arthur Harden received the Nobel Prize in chemistry for research on alcoholic fermentation of carbohydrates and the role of enzymes. Arthur Harden dealt only with the chemical effects of bacteria from 1903 with alcoholic fermentation. Harden discovered that the enzyme zymase, discovered by Eduard Buchner, only produces fermentation in interaction with the coenzyme cozymase. Euler-Chelpin, in turn, convincingly described what happens in sugar fermentation and the action of fermentation enzymes using physical chemistry. This explanation led to the understanding of the important processes taking place in the muscles for the supply of energy.