| Valproic acid utilizes the isoleucine breakdown pathway for its complete β-oxidation. | |
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MedLine Citation:
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PMID: 21843514 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Valproic acid (VPA) is a simple branched medium-chain fatty acid with expanding therapeutic applications beyond its prime anticonvulsant properties. AIMS: (1) To resolve the underlying basis for the interference of valproate with the isoleucine degradative pathway and (2) to shed new light on the enzymology of the β-oxidation pathway of valproate. METHODS: Urine organic acids were analyzed by gas chromatography/mass spectrometry. In vitro studies were performed with heterologously expressed human 2-methyl-3-hydroxybutyryl-CoA dehydrogenase (MHBD) and fibroblasts from controls and a patient with MHBD deficiency using 2-methyl-3-hydroxybutyryl-CoA and 3-hydroxyvalproyl-CoA as substrates. The respective enzymatic activities were measured using optimized HPLC procedures. Short-chain enoyl-CoA hydratase (ECHS1) immunoprecipitation in a human liver homogenate was performed and hydratase activity was measured in the supernatants by HPLC, using crotonyl-CoA and Δ(2(E))-valproyl-CoA as substrates. RESULTS: Patients on valproate therapy had a moderately increased urinary excretion of the isoleucine metabolite 2-methyl-3-hydroxybutyric acid. MHBD was found to convert 3-hydroxyvalproyl-CoA into 3-ketovalproyl-CoA. MHBD activity in control fibroblasts was comparable using both 2-methyl-3-hydroxybutyryl-CoA and 3-hydroxyvalproyl-CoA as substrates. In fibroblasts of a patient with MHBD deficiency, there was no detectable MHBD activity when 3-hydroxyvalproyl-CoA was used as substrate. Samples with immunoprecipitated crotonase had no detectable hydratase activity using both crotonyl-CoA and Δ(2(E))-valproyl-CoA as substrates. DISCUSSION: This work demonstrates for the first time, that MHBD is the unique enzyme responsible for the dehydrogenation of 3-hydroxyvalproyl-CoA. Furthermore, we show that crotonase is the major, if not the single hydratase involved in VPA β-oxidation, next to its role in isoleucine catabolism. |
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Authors:
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Paula B M Luís; Jos P Ruiter; Rob Ofman; Lodewijk Ijlst; Marco Moedas; Luísa Diogo; Paula Garcia; Isabel Tavares de Almeida; Marinus Duran; Ronald J Wanders; Margarida F B Silva |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-8-6 |
Journal Detail:
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Title: Biochemical pharmacology Volume: - ISSN: 1873-2968 ISO Abbreviation: - Publication Date: 2011 Aug |
Date Detail:
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Created Date: 2011-8-16 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0101032 Medline TA: Biochem Pharmacol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Copyright Information:
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Copyright © 2011. Published by Elsevier Inc. |
Affiliation:
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Research Institute for Medicines and Pharmaceutical Sciences, iMed.UL, University of Lisbon, Lisbon, Portugal; Department of Clinical Chemistry and Pediatrics, Academic Medical Center, Amsterdam, Netherlands. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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