The net result is that these carbons are not readily available to serve as keto-acids or carbon skeletons for amino acid synthesis. Some amino acids can be either glucogenic or ketogenic, depending on how they are metabolized. These amino acids are referred to as glucogenic and ketogenic pink. Privacy Policy. Skip to main content.
Chapter 6. Search for:. This example illustrates that if only the connectedness of the graph is considered and the stoichiometric constraints are neglected, then it is likely that non-functional pathways will be postulated.
Another example is monosaccharide metabolism in M. Another drawback of the graph-theoretical approaches mentioned above methods using bipartite graphs excepted is that cycles cannot be easily obtained because they search for linear paths that connect metabolite A to metabolite B not taking into account metabolites that are not synthesized by the path.
One type can occur where there is more than one reaction synthesizing the same product using the same substrate like the reaction converting 3PGP into G3P in Fig. As observed in the above results of the programs PHT and PathFinding, it is not possible to obtain a non-trivial cycle or cyclic pathways like the Krebs cycle using these algorithms, probably also due to the fact that they search for the shortest pathway or the pathway with the lowest weight.
It is a well-known biochemical fact that complex metabolisms involve cyclic pathways, such as the Krebs cycle or the urea cycle. Therefore, algorithms for detecting them are useful. One option for using graph-theoretical methods also for detecting pathways is to use the theory of Petri nets, which are bipartite graphs. Metabolites and reactions are then represented by two different types of nodes cf.
Koch et al. Another option used here is to choose an algebraic treatment such as in EMA, which properly takes into account stoichiometry. The problem of combinatorial explosion in large networks could be solved by using linear programming approaches, by which only specific pathways are computed Beasley and Planes, ; Feist and Palsson, ; Fell and Small, However, a fully automated solution cannot easily be achieved by such approaches either because the proper definition of side metabolites is context dependent.
The authors would like to thank three anonymous referees for very helpful comments. The groups in which L. The scientific atmosphere in the JCB has significantly stimulated this work. Google Scholar. Google Preview. Oxford University Press is a department of the University of Oxford. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide.
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Can sugars be produced from fatty acids? A test case for pathway analysis tools. Oxford Academic. Christoph Kaleta. David A. Associate Editor: Alfonso Valencia. Revision received:.
Cite Cite Luis F. Select Format Select format. Permissions Icon Permissions. Abstract Motivation: In recent years, several methods have been proposed for determining metabolic pathways in an automated way based on network topology. Open in new tab Download slide. Table 1. Queries of PathFinding and retrieved paths present in humans. Paths present in humans.
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Conversion of fatty acids to carbohydrate: application of isotopes to this problem and role of the Krebs cycle as a synthetic pathway. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.
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Biochem Pharmacol. Ilan E, Tirosh O, Madar Z: Triacylglycerol-mediated oxidative stress inhibits nitric oxide production in rat isolated hepatocytes. J Nutr. Antioxid Redox Signal. Download references. The Hebrew University of Jerusalem, P. Box 12, Rehovot, , Israel. You can also search for this author in PubMed Google Scholar.
Correspondence to Oren Tirosh. OT and ZM conceived the experimental design and performed the proofreading of manuscript.
NBH performed the experiments and the statistical analysis and wrote the manuscript. All authors discussed analyses and interpretation, read and approved the final manuscript. Reprints and Permissions. Budick-Harmelin, N. Fatty acids-stress attenuates gluconeogenesis induction and glucose production in primary hepatocytes.
Lipids Health Dis 11, 66 Download citation. Received : 05 January Accepted : 07 June Published : 07 June Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article.
Provided by the Springer Nature SharedIt content-sharing initiative. Skip to main content. Search all BMC articles Search. Download PDF. Abstract Background Hepatic gluconeogenesis tightly controls blood glucose levels in healthy individuals, yet disorders of fatty acids FAs oxidation are characterized by hypoglycemia. Methods Primary rat hepatocytes were pre-treated with FAs prior to gluconeogenic stimuli with glucagon or dexamethasone and cAMP.
Conclusions The present results demonstrate that free-FAs directly inhibit the induced gluconeogenic response in hepatocytes. Background The liver is a major site of systemic metabolic regulation.
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