Enzymology of Amino Acid Conjugation Reactions*

Knights, Kathleen M.; Vessey, Donald A.

doi:10.1016/b978-0-08-046884-6.00422-x

Cited by 5 publications

(4 citation statements)

References 145 publications

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“…The enzymology knowledge of amino acid conjugation is not recognized comprehensively in comparison to that of CYP450 and uridine 5′-diphosphate (UDP) glucuronosyltransferases. 48 A multitude of contaminants bearing hydroxyl groups in their molecules are inevitably being introduced into the soil−plant ecosystem by agricultural biosolids, wastewater irrigation, direct application, and spatial migration. 49 This study demonstrated that DBP as a model was rapidly taken up and metabolized by carrot via enzymatic reaction, predominantly resulting in several phase II saccharide and amino acid conjugates.…”

Section: ■ Introductionmentioning

confidence: 99%

Plant Uptake and Metabolism of 2,4-Dibromophenol in Carrot: In Vitro Enzymatic Direct Conjugation

Sun

Chen

Qian

et al. 2018

J. Agric. Food Chem.

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Plants can extensively uptake organic contaminants from soil and subsequently transform them into various products. Those compounds containing hydroxyl may undergo direct conjugation with endogenous biomolecules in plants, and potentially be preserved as conjugates, thus enabling overlooked risk via consumptions of food crops. In this study, we evaluated the uptake and metabolism of 2,4-dibromophenol (DBP) by both carrot cells and whole plant. DBP was completely removed from cell cultures with a half-life of 10.8 h. Four saccharide conjugates, three amino acid conjugates, and one phase I metabolite were identified via ultraperformance liquid chromatography quadrupole time-of-flight mass spectrometry analysis. The dibromophenol glucopyranoside (glucose conjugate) was quantitated by synthesized standard and accounted for 9.3% of the initial spiked DBP at the end of incubation. The activity of glycosyltransferase was positively related to the production of 2,4-dibromophenol glucopyranoside ( p = 0.02, R = 0.86), implying the role of enzymatic catalysis involved in phase II metabolism.

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Section: ■ Introductionmentioning

confidence: 99%

Plant Uptake and Metabolism of 2,4-Dibromophenol in Carrot: In Vitro Enzymatic Direct Conjugation

Sun

Chen

Qian

et al. 2018

J. Agric. Food Chem.

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“…In the case of sulfotransferases, classic Michaelis–Menten kinetics are followed over a narrow range of substrate concentrations, while some sulfotransferases exhibit positive or negative cooperativity (allosteric sigmoidal enzyme kinetics) when studied over a wide range of substrate concentrations. In vivo studies have shown that the formation of hippuric acid from benzoic acid is limited by the availability of glycine [89] and the administration of exogenous glycine to rats increases the amount of hippuric acid formed [90] . However, the sigmoidal nature of GLYAT makes it extremely difficult to interpret in vivo studies where the concentrations of the substrates or enzyme are not known.…”

Section: Resultsmentioning

confidence: 99%

The glycine N-acyltransferases, GLYAT and GLYATL1, contribute to the detoxification of isovaleryl-CoA - an in-silico and in vitro validation

Kühn

Williams

Dercksen

et al. 2023

Computational and Structural Biotechnology Journal

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“…Unlike the majority of metabolic pathways that follow first-order kinetics in vivo, glycine conjugation is readily saturable. Previous studies have shown that the formation of HA from benzoic acid in vivo is limited by the availability of glycine [27] and that the administration of exogenous glycine to rats increased the amount of HA formed. [8] This phenomenon can be observed in Figure 4A where the rate of HA formation (𝜇M/min) increased as the glycine concentration increased until a linear rate of product formation was observed.…”

Section: Evaluation Of the Kinetic Mechanism Using The Bi-substrate (...mentioning

confidence: 99%

New insights into the catalytic mechanism of human glycine N‐acyltransferase

Sluis

Ungerer

Nortjé

et al. 2017

J Biochem & Molecular Tox

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Even though the glycine conjugation pathway was one of the first metabolic pathways to be discovered, this pathway remains very poorly characterized. The bi-substrate kinetic parameters of a recombinant human glycine N-acyltransferase (GLYAT, E.C. 2.3.1.13) were determined using the traditional colorimetric method and a newly developed HPLC-ESI-MS/MS method. Previous studies analyzing the kinetic parameters of GLYAT, indicated a random Bi-Bi and/or ping-pong mechanism. In this study, the hippuric acid concentrations produced by the GLYAT enzyme reaction were analyzed using the allosteric sigmoidal enzyme kinetic module. Analyses of the initial rate (v) against substrate concentration plots, produced a sigmoidal curve (substrate activation) when the benzoyl-CoA concentrations was kept constant, whereas the plot with glycine concentrations kept constant, passed through a maximum (substrate inhibition). Thus, human GLYAT exhibits mechanistic kinetic cooperativity as described by the Ferdinand enzyme mechanism rather than the previously assumed Michaelis-Menten reaction mechanism.

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Enzymology of Amino Acid Conjugation Reactions*

Cited by 5 publications

References 145 publications

Plant Uptake and Metabolism of 2,4-Dibromophenol in Carrot: In Vitro Enzymatic Direct Conjugation

Plant Uptake and Metabolism of 2,4-Dibromophenol in Carrot: In Vitro Enzymatic Direct Conjugation

The glycine N-acyltransferases, GLYAT and GLYATL1, contribute to the detoxification of isovaleryl-CoA - an in-silico and in vitro validation

New insights into the catalytic mechanism of human glycine N‐acyltransferase

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