Transient-phase energetics of the oxidative deamination ofL-glutamate byL-glutamate dehydrogenase and NADP: A reaction with a large negative heat capacity of activation

Biopolymers ◽  
1981 ◽  
Vol 20 (5) ◽  
pp. 879-889 ◽  
Author(s):  
Alan H. Colen ◽  
Richard T. Medary ◽  
Harvey F. Fisher
Keyword(s):  
Heat Capacity ◽  
Glutamate Dehydrogenase ◽  
Transient Phase ◽  
Oxidative Deamination

Properties of NAD-dependent glutamate dehydrogenase from the tylosin producer Streptomyces fradiae

1997 ◽  
Vol 43 (11) ◽  
pp. 1005-1010 ◽  
Author(s):  
Kien Trung Nguyen ◽  
Lieu Thi Nguyen ◽  
Jan Kopecký ◽  
Vladislav Běhal
Keyword(s):  
Key Words ◽  
Glutamate Dehydrogenase ◽  
Reductive Amination ◽  
Divalent Cations ◽  
Ammonium Assimilation ◽  
Alkaline Ph ◽  
Streptomyces Fradiae ◽  
Oxidative Deamination

Glutamate dehydrogenase is an enzyme responsible for ammonium assimilation and glutamate catabolism in organisms. The tylosin producer Streptomyces fradiae possesses both NADP- and NAD-dependent glutamate dehydrogenases. The latter enzyme was purified 498-fold with a 7.5% recovery by a six-step protocol. The enzyme is composed of two subunits, each of Mr 47 000, and could form active aggregates of four or eight subunits. Its activity was inactivated by alkaline pH or temperatures of −20 °C or above 40 °C. Activities assayed in the direction of oxidative deamination and reductive amination were optimal at pH 9.2 and 8.8, respectively, and at temperatures of 30–35 °C. No activity was found when NAD(H) was replaced with NADP(H). The Km values were 32.2 mM for L-glutamate, 0.3 mM for NAD+, 3.4 mM for 2-ketoglutarate, 14.2 mM for NH4+, and 0.05 mM for NADH. Deamination activity was partially inhibited by adenyl nucleotides and several divalent cations; amination activity was not affected by the nucleotides but significantly inhibited by Cu2+ or Ni2+.Key words: Streptomyces fradiae, NAD-dependent glutamate dehydrogenase, purification, properties.

A Legionella effector ADP-ribosyltransferase inactivates glutamate dehydrogenase

2020 ◽  
Author(s):  
Miles H. Black ◽  
Adam Osinski ◽  
Marcin Gradowski ◽  
Kelly A. Servage ◽  
Krzysztof Pawłowski ◽  
...  
Keyword(s):  
Glutamate Dehydrogenase ◽  
Legionella Pneumophila ◽  
Structural Diversity ◽  
Binding Pocket ◽  
Metabolic Enzyme ◽  
Specific Class ◽  
Oxidative Deamination ◽  
Natural Hosts ◽  
Adp Ribosyltransferase ◽  
Bioinformatic Approach

AbstractADP-ribosyltransferases (ARTs) are a widespread superfamily of enzymes frequently employed in pathogenic strategies of bacteria. Legionella pneumophila, the causative agent of Legionnaire’s disease, has acquired over 330 translocated effectors that showcase remarkable biochemical and structural diversity. Here we took a bioinformatic approach to search the Legionella effector repertoire for additional divergent members of the ART superfamily and identified an ART domain in Lpg0181. We show that L. pneumophila Lpg0181 targets a specific class of 120-kDa NAD+-dependent glutamate dehydrogenase (GDH) enzymes found in fungi and protists, including many natural hosts of Legionella. Lpg0181 targets a conserved arginine residue in the NAD+ -binding pocket of GDH, thereby blocking oxidative deamination of glutamate. While intracellular pathogens employ diverse virulence mechanisms to overcome host-limited nutrient availability, Lpg0181 is––to the best of our knowledge––the first example of a Legionella effector which directly targets a host metabolic enzyme.

scholarly journals Crystal structure of a chimaeric bacterial glutamate dehydrogenase

2016 ◽  
Vol 72 (6) ◽  
pp. 462-466 ◽  
Author(s):  
Tânia Oliveira ◽  
Michael A. Sharkey ◽  
Paul C. Engel ◽  
Amir R. Khan
Keyword(s):  
Crystal Structure ◽  
Glutamate Dehydrogenase ◽  
Rigid Bodies ◽  
Nucleotide Binding Domain ◽  
Oxidative Deamination ◽  
E Coli ◽  
Cofactor Binding ◽  
Signature Sequences ◽  
Clostridium Symbiosum ◽  
Domain I

Glutamate dehydrogenases (EC 1.4.1.2–4) catalyse the oxidative deamination of L-glutamate to α-ketoglutarate using NAD(P)+as a cofactor. The bacterial enzymes are hexameric, arranged with 32 symmetry, and each polypeptide consists of an N-terminal substrate-binding segment (domain I) followed by a C-terminal cofactor-binding segment (domain II). The catalytic reaction takes place in the cleft formed at the junction of the two domains. Distinct signature sequences in the nucleotide-binding domain have been linked to the binding of NAD+versusNADP+, but they are not unambiguous predictors of cofactor preference. In the absence of substrate, the two domains move apart as rigid bodies, as shown by the apo structure of glutamate dehydrogenase fromClostridium symbiosum. Here, the crystal structure of a chimaeric clostridial/Escherichia colienzyme has been determined in the apo state. The enzyme is fully functional and reveals possible determinants of interdomain flexibility at a hinge region following the pivot helix. The enzyme retains the preference for NADP+cofactor from the parentE. colidomain II, although there are subtle differences in catalytic activity.

scholarly journals Anticonvulsant Drugs, Brain Glutamate Dehydrogenase Activity and Oxygen Consumption

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Lourdes A. Vega Rasgado ◽  
Guillermo Ceballos Reyes ◽  
Fernando Vega-Díaz
Keyword(s):  
Oxygen Consumption ◽  
Glutamate Dehydrogenase ◽  
Reductive Amination ◽  
Pyridoxal Phosphate ◽  
Neuronal Excitability ◽  
Aminooxyacetic Acid ◽  
Oxidative Deamination ◽  
Key Enzyme

Glutamate dehydrogenase (GDH, E.C. 1.4.1.3.) is a key enzyme for the biosynthesis and modulation of glutamate (GLU) metabolism and an indirect γ-aminobutyric acid (GABA) source, here we studied the effect of anticonvulsants such as pyridoxal phosphate (PPAL), aminooxyacetic acid (AAOA), and hydroxylamine (OHAMINE) on GDH activity in mouse brain. Moreover, since GLU is a glucogenic molecule and anoxia is a primary cause of convulsions, we explore the effect of these drugs on oxygen consumption. Experiments were performed in vitro as well as in vivo for both oxidative deamination of GLU and reductive amination of α-ketoglutarate (αK). Results in vitro showed that PPAL decreased oxidative deamination of GLU and oxygen consumption, whereas AAOA and OHAMINE inhibited GDH activity competitively and also inhibited oxygen consumption when αK reductive amination was carried out. In contrast, results showed that in vivo, all anticonvulsants enhanced GLU utilization by GDH and also decreased oxygen consumption. Together, results suggest that GDH activity has repercussions on oxygen consumption, which may indicate that the enzyme activity is highly regulated by energy requirements for metabolic activity. Besides, GDH may participate in regulation of GLU and, indirectly GABA levels, hence in neuronal excitability, becoming a key enzyme in seizures mechanism.

NADPH binding induced proton ionization as a cause of nonlinear heat capacity changes in glutamate dehydrogenase

Biochemistry ◽  
1986 ◽  
Vol 25 (10) ◽  
pp. 2910-2915 ◽  
Author(s):  
Harvey F. Fisher ◽  
Steven Maniscalco ◽  
Cindy Wolfe ◽  
R. Srinivasan
Keyword(s):  
Heat Capacity ◽  
Glutamate Dehydrogenase ◽  
Heat Capacity Changes

scholarly journals The pathway of glutamate metabolism in rat brain mitochondria

1977 ◽  
Vol 168 (3) ◽  
pp. 521-527 ◽  
Author(s):  
Steven C. Dennis ◽  
John B. Clark
Keyword(s):  
Rat Brain ◽  
Glutamate Dehydrogenase ◽  
Brain Mitochondria ◽  
Ammonia Production ◽  
Glutamate Metabolism ◽  
Oxidative Deamination ◽  
Rat Brain Mitochondria ◽  
Major Route

1. The pathway of glutamate metabolism in non-synaptic rat brain mitochondria was investigated by measuring glutamate, aspartate and ammonia concentrations and oxygen uptakes in mitochondria metabolizing glutamate or glutamine under various conditions. 2. Brain mitochondria metabolizing 10mm-glutamate in the absence of malate produce aspartate at 15nmol/min per mg of protein, but no detectable ammonia. If amino-oxyacetate is added, the aspartate production is decreased by 80% and ammonia production is now observed at a rate of 6.3nmol/min per mg of protein. 3. Brain mitochondria metabolizing glutamate at various concentrations (0–10mm) in the presence of 2.5mm-malate produce aspartate at rates that are almost stoicheiometric with glutamate disappearance, with no detectable ammonia production. In the presence of amino-oxyacetate, although the rate of aspartate production is decreased by 75%, ammonia production is only just detectable (0.3nmol/min per mg of protein). 4. Brain mitochondria metabolizing 10mm-glutamine and 2.5mm-malate in States 3 and 4 were studied by using glutamine as a source of intramitochondrial glutamate without the involvement of mitochondrial translocases. The ammonia production due to the oxidative deamination of glutamate produced from the glutamine was estimated as 1nmol/min per mg of protein in State 3 and 3nmol/min per mg of protein in State 4. 5. Brain mitochondria metabolizing 10mm-glutamine in the presence of 1mm-amino-oxyacetate under State-3 conditions in the presence or absence of 2.5mm-malate showed no detectable aspartate production. In both cases, however, over the first 5min, ammonia production from the oxidative deamination of glutamate was 21–27nmol/min per mg of protein, but then decreased to approx. 1–1.5nmol/min per mg. 6. It is concluded that the oxidative deamination of glutamate by glutamate dehydrogenase is not a major route of metabolism of glutamate from either exogenous or endogenous (glutamine) sources in rat brain mitochondria.

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