Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.6.1.19 (GABA transaminase)
 808 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The enzyme-induced or 'suicide' step by which the substrate analogue ethanolamine O-sulphate inactivates 4-aminobutyrate aminotransferase occurs at a rate that is one-tenth that observed for the release of the products of beta-elimination, namely ammonia, acetaldehyde and sulphate. An additional reversible reaction not leading to inactivation can be detected spectrally and this decreases the rates of both beta-elimination and inactivation. This reaction is ascribed to a step on the normal transamination path, although complete transamination does not occur significantly. The 14C moiety of radiolabelled ethanolamine O-sulphate is stably bound to the inactive enzyme in the proportion of 1 mol/mol of active site. The 35S-labelled sulphate moiety is not bound after inactivation, showing that beta-elimination must precede inactivation.
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PMID:The reaction of ethanolamine O-sulphate with 4-aminobutyrate aminotransferase. 731 26

The aldehyde produced from the oxidative deamination of primary and secondary amines by the monoamine oxidases (EC 1.4.3.4; MAO) or the semicarbazide-sensitive amine oxidases (EC 1.4.3.6; SSAO) may be determined followed reaction at elevated temperatures with 2-diphenylacetyl-1,3-indandione-1-hydrazone (DIH), separation by high-performance chromatography liquid (C-8 column, eluting isocratically with acetonitrile, ammonium acetate, water) and fluorimetric detection (excitation and emission wavelengths 430 and 525 nm). The detection limits for benzaldehyde, p-hydroxybenzaldehyde and 2-phenylacetaldehyde were 125 nM, 150 and 62.3 nM, respectively. Thus the assay is appropriate for determination of amine oxidase activities towards benzylamine, 2-phenylethylamine and tyramine. The fluorescence of the DIH adduct with indole-3-aldehyde was strongly quenched, giving a relatively high detection limit (17.5 microM). The detection limit was lower (3.8 microM) when the absorbance at 430 nm was monitored. Enzyme activities determined by this procedure were shown to be linear with enzyme-protein concentration (rat liver mitochondria). The presence of 1-2 mM semicarbazide, necessary for determining MAO activities in samples also containing SSAO, did not adversely affect the derivatization reaction. The DIH-aldehyde adducts were sufficiently stable to permit their storage at low temperatures prior to assay. The product produced by reaction of 5-hydroxyindole acetaldehyde with DIH had no significant fluorescence and too low an absorbance at 430 nm to allow its determination for assay of activities towards 5-HT. This procedure can also measure succinic semialdehyde (detection limit 240 nM) and thus would be applicable to the determination of GABA transaminase activity.
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PMID:Determination of monoamine oxidase activity by HPLC with fluorimetric detection. 1059 Oct 46