| Abnormal tricarboxylic acid cycle metabolites in isovaleric acidaemia. | |
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MedLine Citation:
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PMID: 19343532 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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BACKGROUND: Although a number of abnormal diagnostic metabolites have previously been described in the urine of patients with isovaleric acidaemia (IVA), they do not fully explain the clinical symptoms associated with this disease. METHODS: On the basis of our current understanding of the TCA cycle and IVA, we predicted a number of abnormal methylated TCA cycle metabolites, initiated by methylsuccinic acid. We subsequently obtained characteristic gas chromatography-mass spectrometry elution times and mass spectra of the chemically synthesized predicted compounds and screened the urine of 6 IVA patients and 24 age-matched controls. Further proof for our findings was generated from a series of in vitro enzyme reactions using the chemically synthesized standards as substrates to their respective TCA cycle enzymes. RESULTS: Apart from the previously described methylsuccinic and methylfumaric acid, 3-methylmalic acid, (2R,3S)- and (2R,3R)-methylcitric acid and 2-methyl-cis-aconitic acid were detected in the urine of all 6 IVA patients in increased amounts. Additionally, although not directly determined, the in vitro enzyme reaction using of 3-methylmalic acid and malate dehydrogenase, in conjunction with the detection of 2-ketobutyric acid in the urine of all 6 IVA patients, strongly suggests an additional synthesis of 3-methyloxaloacetic acid by the same cycle. CONCLUSION: Not only do these newly identified metabolites serve as additional diagnostic markers to those previously identified in IVA, but due to the structural arrangements of the (2R,3R)-methylcitric acid and 2-methyl-cis-aconitinic acid-derived 2-methylisocitric acid, inhibition of normal TCA cycle metabolism results at citrate synthase and isocitrate dehydrogenase, respectively. SYNOPSIS: Methylsuccinic acid acts as the initiating substrate to a series of abnormal, potentially harmful, methylated tricarboxylic acid cycle metabolites in isovaleric acidaemia. |
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Authors:
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D T Loots |
Publication Detail:
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Type: Journal Article Date: 2009-04-05 |
Journal Detail:
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Title: Journal of inherited metabolic disease Volume: 32 ISSN: 1573-2665 ISO Abbreviation: J. Inherit. Metab. Dis. Publication Date: 2009 Jun |
Date Detail:
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Created Date: 2009-05-27 Completed Date: 2009-08-19 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 7910918 Medline TA: J Inherit Metab Dis Country: Netherlands |
Other Details:
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Languages: eng Pagination: 403-11 Citation Subset: IM |
Affiliation:
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School for Physical and Chemical Sciences, Centre of Metabolomics, Division of Biochemistry, North-West University, Hoffman Street, Private Bag X6001, Box 269, Potchefstroom 2531, South Africa. dutoit.loots@nwu.ac.za |
| Data Bank Information | |
Bank Name/Acc. No.:
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OMIM/243500 |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Amino Acid Metabolism, Inborn Errors
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blood,
complications,
metabolism*,
urine* Case-Control Studies Child, Preschool Citric Acid Cycle / physiology* Gas Chromatography-Mass Spectrometry Humans Infant Infant, Newborn Models, Biological Pentanoic Acids / blood*, metabolism Spectrometry, Mass, Electrospray Ionization |
| Chemical | |
Reg. No./Substance:
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0/Pentanoic Acids; 503-74-2/isovaleric acid |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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