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231224s2016 xx |||||o 00| ||eng c |
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|a 10.1016/j.plaphy.2016.07.015
|2 doi
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|a pubmed24n0875.xml
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|a (DE-627)NLM26271860X
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|a (NLM)27448794
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|a (PII)S0981-9428(16)30282-0
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|a DE-627
|b ger
|c DE-627
|e rakwb
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|a eng
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|a Mauve, Caroline
|e verfasserin
|4 aut
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|a Kinetic commitment in the catalysis of glutamine synthesis by GS1 from Arabidopsis using 14N/15N and solvent isotope effects
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|c 2016
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|a Text
|b txt
|2 rdacontent
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|a ƒaComputermedien
|b c
|2 rdamedia
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|a ƒa Online-Ressource
|b cr
|2 rdacarrier
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|a Date Completed 07.04.2017
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|a Date Revised 30.09.2020
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|a published: Print-Electronic
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|a Citation Status MEDLINE
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|a Copyright © 2016 Elsevier Masson SAS. All rights reserved.
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|a Glutamine synthetase (GS, EC 6.3.1.2) catalyzes the production of glutamine from glutamate, ammonium and ATP. Although being essential in plants for N assimilation and recycling, kinetic commitments and transition states of the reaction have not been clearly established yet. Here, we examined 12C/13C, 14N/15N and H2O/D2O isotope effects in Arabidopsis GS1 catalysis and compared to the prokaryotic (Escherichia coli) enzyme. A14N/15N isotope effect (15V/K ≈ 1.015, with respect to substrate NH4+) was observed in the prokaryotic enzyme, indicating that ammonium utilization (deprotonation and/or amidation) was partially rate-limiting. In the plant enzyme, the isotope effect was inverse (15V/K = 0.965), suggesting that the reaction intermediate is involved in an amidation-deamidation equilibrium favoring 15N. There was no 12C/13C kinetic isotope effect (13V/K = 1.000), suggesting that the amidation step of the catalytic cycle involves a transition state with minimal alteration of overall force constants at the C-5 carbon. Surprisingly, the solvent isotope effect was found to be inverse, that is, with a higher turn-over rate in heavy water (DV ≈ 0.5), showing that restructuration of the active site due to displacement of H2O by D2O facilitates the processing of intermediates
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|a Journal Article
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|a Amidation
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|a Catalysis
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|a Glutamine
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|a Isotope effect
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|a Kinetic commitment
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|a Arabidopsis Proteins
|2 NLM
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|a Carbon Isotopes
|2 NLM
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|a Nitrogen Isotopes
|2 NLM
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|a Solvents
|2 NLM
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|a Glutamine
|2 NLM
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|a 0RH81L854J
|2 NLM
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| 650 |
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|a GLN1;2 protein, Arabidopsis
|2 NLM
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| 650 |
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|a EC 6.3.1.2
|2 NLM
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| 650 |
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|a Glutamate-Ammonia Ligase
|2 NLM
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| 650 |
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|a EC 6.3.1.2
|2 NLM
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| 700 |
1 |
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|a Giraud, Nicolas
|e verfasserin
|4 aut
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|a Boex-Fontvieille, Edouard R A
|e verfasserin
|4 aut
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|a Antheaume, Ingrid
|e verfasserin
|4 aut
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|a Tea, Illa
|e verfasserin
|4 aut
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|a Tcherkez, Guillaume
|e verfasserin
|4 aut
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| 773 |
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|i Enthalten in
|t Plant physiology and biochemistry : PPB
|d 1991
|g 108(2016) vom: 22. Nov., Seite 203-211
|w (DE-627)NLM098178261
|x 1873-2690
|7 nnns
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| 773 |
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|g volume:108
|g year:2016
|g day:22
|g month:11
|g pages:203-211
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|u http://dx.doi.org/10.1016/j.plaphy.2016.07.015
|3 Volltext
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|d 108
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|b 22
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|h 203-211
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