Sir Hans Adolf Krebs ( or ) (25 August 1900 – 22 November 1981) was a German-born British
physician and
biochemist. He was the pioneer scientist in study of
cellular respiration, a
biochemical pathway in cells for
production of energy. He is best known for his discoveries of two important chemical reactions in the body, namely the
urea cycle and the
citric acid cycle. The latter, the key sequence of metabolic reactions that produces energy in cells, often eponymously known as the "Krebs cycle", earned him a
Nobel Prize in Physiology or Medicine in 1953. With
Hans Kornberg, he also discovered the
glyoxylate cycle, which is a slight variation of the citric acid cycle found in plants, bacteria,
protists, and
fungi.