Krebs cycle discovery

German-British scientist Hans Krebs, who made important contributions to the study of many metabolic pathways and reaction mechanisms. For the discovery of the Krebs cycle, he won the Nobel Prize in 1953. 

At the University of Freiburg (1932), he discovered a series of chemical reactions (now known as the urea cycle) by which ammonia is converted to urea in mammalian tissue. For his discoveries of chemical reactions in living organisms now known as the citric acid or Krebs cycle, he was awarded the 1953 Nobel Prize for physiology or medicine. These reactions involve the... 

This discovery was in the end even more important than it at first seemed, since it became clear in due course (1) that fatty acids also gave rise to acetyl CoA in their oxidation (Topic 20), (2) that several amino acids also did so (Topic 23) and (3) that some amino acids were converted directly into one or other of the Krebs cycle... 

The reactions in which pyruvic acid is oxidized to form CO2 and acetic acid are of the greatest significance since they constitute the link between glycolysis and the Krebs cycle. These reactions involve a considerable number of coenzymes thiamine pyrophosphate, lipoic acid, Co A, and NAD. Much of our knowledge of pyruvic acid oxidation depended on the discovery of CoA and lipoic acid, and it might be useful to review the biochemistry of lipoic acid before we enter into more detail. Refer to the chapter on vitamins for a review of the metabolism and catabolism of thiamine, CoA, and NAD. 

In 1936, Harland Wood and Chester Workman made the fundamental discovery that non-photosyuthetic, heterotrophic organisms utilize COg for the synthesis of compounds related to those in the Krebs cycle. CO2 fixation was later observed with extracts of bacterial and animal cells. 

The citric acid cycle was discovered independently at about the same time in 1937 by Martius and Knoop and by Krebs. The discovery permitted the correlation of many isolated facts. 

BOX 10-B DISCOVERY OF THE CITRIC ACID CYCLE (KREBS TRICARBOXYLIC ACID CYCLE)... 

The fumarate released in the urea cycle links the urea cycle with the TCA cycle. This fumarate is hydrated to malate, which is oxidized to oxaloacetate. The carbons of oxaloacetate can stay in the TCA cycle by condensation with acetyl-CoA to form citrate, or they can leave the TCA cycle either by gluconeogenesis to form glucose or by transamination to form aspartate as shown in figure 22.9. Because Krebs was involved in the discoveries of both the urea cycle and the TCA cycle, the interaction between the two cycles shown in figure 22.9 is sometimes referred to as the Krebs bicycle. 

F.L. Holmes. 1980. Hans Krebs and the discovery of the ornithine cycle Fed. Proc. 39 216-225. (PubMed)... 

Many years after his discovery of the citric acid cycle, when asked to reflect upon why he had succeeded when so many other brilliant scientists had failed to elucidate this mechanism, Krebs replied in part,... 

Albert Szent-Gyorgyi was surely one of the most important scientists of the twentieth century. His research interests included vitamins, enzymatic oxidation mechanisms, muscle contraction, and cancer. He won the 1937 Nobel Prize in physiology or medicine for his discovery of vitamin C and for his studies on the Krebs, or citric acid, cycle. 

Is it tme that Hans Krebs paper in 1937, reporting the discovery of the citric acid cycle, was rejected by the jonmal Nature, so it was snbmitted to the jonmal Enzymologia were it was pnblished ... 

After Sir Hans Adolf Krebs (Nobel Prize, 1953, for his discovery of the citric acid cycle ) who identified and studied the cycle. See Krebs, H. A. Perspect. Biol. Med., 1970,74,154. 

Following on these fundamental discoveries, Krebs formulated the cycle ... 

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