| Kinetic studies on the inhibition of GABA-T by gamma-vinyl GABA and taurine. | |
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MedLine Citation:
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PMID: 14567543 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Gamma-aminobutyric acid transaminase (GABA-T, EC 2.6.1.19) is a pyridoxal phosphate (PLP) dependent enzyme that catalyzes the degradation of gamma-aminobutyric acid. The kinetics of this reaction are studied in vitro, both in the absence, and in the presence of two inhibitors: gamma-vinyl GABA (4-aminohex-5-enoic acid), and a natural product, taurine (ethylamine-2-sulfonic acid). A kinetic model that describes the transamination process is proposed. GABA-T from Pseudomonas fluorescens is inhibited by gamma-vinyl GABA and taurine at concentrations of 51.0 and 78.5 mM. Both inhibitors show competitive inhibition behavior when GABA is the substrate and the inhibition constant (Ki) values for gamma-vinyl GABA and taurine were found to be 26 +/- 3 mM and 68 +/- 7 mM respectively. The transamination process of alpha-ketoglutarate was not affected by the presence of gamma-vinyl GABA, whereas, taurine was a noncompetitive inhibitor of GABA-T when alpha-ketoglutarate was the substrate. The inhibition dissociation constant (Kii) for this system was found to be 96 +/- 10 mM. The Michaelis-Menten constant (Km) in the absence of inhibition, was found to be 0.79 +/- 0.11 mM, and 0.47 +/- 0.10 mM for GABA and alpha-ketoglutarate respectively. |
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Authors:
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Saba A J Sulaiman; Fakhr Eldin O Suliman; Samira Barghouthi |
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Publication Detail:
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Type: Comparative Study; Journal Article |
Journal Detail:
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Title: Journal of enzyme inhibition and medicinal chemistry Volume: 18 ISSN: 1475-6366 ISO Abbreviation: J Enzyme Inhib Med Chem Publication Date: 2003 Aug |
Date Detail:
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Created Date: 2003-10-21 Completed Date: 2004-05-03 Revised Date: 2007-03-21 |
Medline Journal Info:
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Nlm Unique ID: 101150203 Medline TA: J Enzyme Inhib Med Chem Country: England |
Other Details:
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Languages: eng Pagination: 297-301 Citation Subset: IM |
Affiliation:
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Sultan Qaboos University, Department of Chemistry, College of Science, Box 36, Al-Khod 123, Sultanate of Oman. |
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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drug effects,
metabolism* Enzyme Inhibitors / pharmacology* Kinetics Taurine / pharmacology* Vigabatrin / pharmacology* |
| Chemical | |
Reg. No./Substance:
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0/Enzyme Inhibitors; 107-35-7/Taurine; 60643-86-9/Vigabatrin; EC 2.6.1.19/4-Aminobutyrate Transaminase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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