born Aug. 25, 1900, Hildesheim, Ger. died Nov. 22, 1981, Oxford, Eng. German-born British biochemist. He fled Nazi Germany for England in 1933, where he taught at the Universities of Sheffield and Oxford. He was the first to describe the urea cycle (1932). He and Fritz Lipmann (1899-1986) received a 1953 Nobel Prize for their discovery in living organisms of the series of chemical reactions known as the tricarboxylic acid cycle (also called the citric acid cycle or Krebs cycle), a discovery of vital importance to a basic understanding of cell metabolism and molecular biology