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| | I am 22 years old and my name is Rickey Whitfield. I life in Jersey City (United States).<br><br>Here is my web site ... [https://swellbottle.zendesk.com/entries/45854619-Dog-Training-Collar-Make-Your-Dog-Stay-In-Your-Yard beagle dog training] |
| '''Anaplerotic reactions''' (from the Greek [http://en.wiktionary.org/wiki/%E1%BC%80%CE%BD%CE%AC#Ancient_Greek ἀνά]= 'up' and [http://en.wiktionary.org/wiki/%CF%80%CE%BB%CE%B7%CF%81%CF%8C%CF%89 πληρόω]= 'to fill') are those that form intermediates of a metabolic pathway. Examples of such are found in the Tricarboxylic acid (TCA) Cycle (also called the Krebs or [[citric acid cycle]]). In normal function of this cycle for respiration, concentrations of TCA intermediates remain constant; however, many biosynthetic reactions also use these molecules as a substrate. Anaplerosis is the act of replenishing TCA cycle intermediates that have been extracted for biosynthesis (in what are called '''[[cataplerotic]] reactions''').
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| The TCA Cycle is a hub of metabolism, with central importance in both energy production and biosynthesis. Therefore, it is crucial for the cell to regulate concentrations of TCA Cycle metabolites in the mitochondria. Anaplerotic flux must balance cataplerotic flux in order to retain homeostasis of cellular metabolism.<ref>{{cite journal |author=Owen O, Kalhan S, Hanson R |title=The key role of anaplerosis and cataplerosis for citric acid cycle function |journal=J. Biol. Chem. |volume=277 |issue=34 |pages=30409–12 |year=2002 |pmid=12087111 |url=http://www.jbc.org/cgi/content/full/277/34/30409 |doi=10.1074/jbc.R200006200}}</ref>
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| == Reactions of anaplerotic metabolism ==
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| There are 4 major reactions classed as anaplerotic, yet the production of oxaloacetate from pyruvate has, it is estimated, the most physiologic importance.
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| {| class="wikitable"
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| | '''From''' || '''To''' || '''Reaction''' || '''Notes'''
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| | [[Pyruvate]] || [[oxaloacetate]] || pyruvate + HCO<sub>3</sub><sup>-</sup> + ATP <math>\longrightarrow</math> oxaloacetate + ADP + P<sub>i</sub> + H<sub>2</sub>O || This reaction is catalysed by [[pyruvate carboxylase]], an [[enzyme]] activated by [[Acetyl coenzyme A|Acetyl-CoA]], indicating a lack of [[oxaloacetate]]. It occurs in animal [[mitochondria]]. Most important anaplerotic reaction depending on severity, deficiency causes lactic acidosis, severe psychomotor deficiency or death in infancy [http://www.omim.org/entry/266150]
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| [[Pyruvate]] can also be converted to [[malic acid|L-malate]], another intermediate, in a similar way.
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| | [[Aspartate]] || [[oxaloacetate]] || - || This is a reversible reaction forming oxaloacetate from [[aspartate]] in a [[transamination]] reaction, via [[aspartate transaminase]].
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| | [[Glutamate]] || α-[[ketoglutarate]]|| [[glutamate]] + NAD<sup>+</sup> + H<sub>2</sub>O <math>\longrightarrow</math> NH<sub>4</sub><sup>+</sup> + α-ketoglutarate + NADH + H<sup>+</sup>. || This reaction is catalysed by [[glutamate-dehydrogenase]].
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| | [[β-oxidation|β-Oxidation]] of [[fatty acid]]s || [[succinyl-CoA]] || - || When odd-chain [[fatty acids]] are oxidized, one molecule of succinyl-CoA is formed per fatty acid. The final enzyme is [[methylmalonyl-CoA mutase]]. [[Triheptanoin]] (fat with three heptanoic (C7:0) fatty acids) may be used to treat pyruvate carboxylase deficiency
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| | [[adenylosuccinate]] || [[fumarate]] || adenylosuccinate <math>\longrightarrow</math> AMP + fumarate || This reaction is catalysed by [[adenylosuccinate lyase]] and occurs in purine synthesis and purine nucleotide cycle. Defect of this enzyme [http://www.omim.org/entry/608222] causes psychomotor retardation.
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| |}
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| The [[malate]] is created by [[Phosphoenolpyruvate carboxylase|PEP carboxylase]] and [[malate dehydrogenase]] in the [[cytosol]]. Malate, in the [[mitochondrial matrix]], can be used to make [[pyruvate]] (catalyzed by [[Malate dehydrogenase (decarboxylating)|malic enzyme]]) or [[oxaloacetic acid]], both of which can enter the [[citric acid cycle]].
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| Glutamine can also be used to produce oxaloacetate during anaplerotic reactions in various cell types through "glutaminolysis" which is also seen in many c-Myc transformed cells.<ref>DeBerardinis, et al The biology of cancer:metabolic reprogramming fuels cell growth and proliferation. Cell Metabolism 7, January 2008</ref>
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| == Diseases of anaplerotic metabolism ==
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| Pyruvate carboxylase deficiency is an inherited metabolic disorder where anaplerosis is greatly reduced. Other anaplerotic substrates such as the odd-carbon-containing triglyceride [[Triheptanoin]] can be used to treat this disorder.
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| ==References==
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| <references/>
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| {{Citric acid cycle enzymes}}
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| {{DEFAULTSORT:Anaplerotic Reactions}}
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| [[Category:Cellular respiration]]
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| {{metabolism-stub}}
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| [[it: Reazioni anaplerotiche]]
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I am 22 years old and my name is Rickey Whitfield. I life in Jersey City (United States).
Here is my web site ... beagle dog training