| Development of a stable-isotope dilution assay for gamma-aminobutyric acid (GABA) transaminase in isolated leukocytes and evidence that GABA and beta-alanine transaminases are identical. | |
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MedLine Citation:
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PMID: 11238307 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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BACKGROUND: Several methods have been published for measuring gamma-aminobutyric acid transaminase (GABA-T) activity, but these methods are either impracticable because of the use of radioisotopes or insufficiently sensitive to determine small enzyme activities in leukocyte extracts. We developed a direct and sensitive enzyme method. METHODS: We developed a stable-isotope dilution method for the measurement of [15N]glutamic acid derived from [15N]GABA and alpha-ketoglutaric acid, catalyzed by GABA-T. The method for analysis of [15N]glutamic acid comprised a solid-phase extraction procedure to isolate this analyte from incubation samples. After derivatization, [15N]glutamic acid was quantified by gas chromatography-mass spectrometry relative to its 2H5-labeled internal standard. In addition to [15N]GABA, [15N]beta-alanine was a cosubstrate. RESULTS: GABA-T-deficient lymphoblasts showed diminished enzyme activity, with both [15N]GABA and [15N]beta-alanine as substrate. Vigabatrin inhibited the enzyme activity for both substrates. CONCLUSIONS: The activity of GABA-T can be accurately determined by our procedure using 15N-labeled substrate, measuring the formation of [15N]glutamic acid. Our results with [15N]beta-alanine indicate that GABA and beta-alanine transaminases are identical. |
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Authors:
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D S Schor; E A Struys; B M Hogema; K M Gibson; C Jakobs |
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Publication Detail:
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Type: In Vitro; Journal Article |
Journal Detail:
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Title: Clinical chemistry Volume: 47 ISSN: 0009-9147 ISO Abbreviation: Clin. Chem. Publication Date: 2001 Mar |
Date Detail:
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Created Date: 2001-03-12 Completed Date: 2001-03-22 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 9421549 Medline TA: Clin Chem Country: United States |
Other Details:
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Languages: eng Pagination: 525-31 Citation Subset: IM |
Affiliation:
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Metabolic Unit, Department of Clinical Chemistry, University Hospital Vrije Universiteit, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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4-Aminobutyrate Transaminase
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chemistry,
metabolism* Alanine Transaminase / chemistry, metabolism* Humans Indicator Dilution Techniques Lymphocytes / enzymology* Nitrogen Isotopes Spectrometry, Mass, Electrospray Ionization beta-Alanine / metabolism |
| Chemical | |
Reg. No./Substance:
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0/Nitrogen Isotopes; 107-95-9/beta-Alanine; EC 2.6.1.19/4-Aminobutyrate Transaminase; EC 2.6.1.2/Alanine Transaminase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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