scholarly journals Kinetic Properties of Allosteric Adenosine Monophosphate Nucleosidase from Azotobacter vinelandii

1974 ◽  
Vol 249 (6) ◽  
pp. 1729-1736 ◽  
Author(s):  
Vern L. Schramm
Keyword(s):  
Azotobacter Vinelandii ◽  
Adenosine Monophosphate ◽  
Kinetic Properties

scholarly journals AMPK-Mediated Regulation of Alpha-Arrestins and Protein Trafficking

2019 ◽  
Vol 20 (3) ◽  
pp. 515 ◽  
Author(s):  
Allyson F. O’Donnell ◽  
Martin C. Schmidt
Keyword(s):  
Glucose Uptake ◽  
Protein Trafficking ◽  
Transmembrane Domain ◽  
Carbon Sources ◽  
Cellular Metabolism ◽  
Glucose Transporters ◽  
Adenosine Monophosphate ◽  
Kinetic Properties ◽  
Glucose Limitation ◽  
Additional Layer

Abstract: The adenosine monophosphate-activated protein kinase (AMPK) plays a central role in the regulation of cellular metabolism. Recent studies reveal a novel role for AMPK in the regulation of glucose and other carbohydrates flux by controlling the endocytosis of transporters. The first step in glucose metabolism is glucose uptake, a process mediated by members of the GLUT/SLC2A (glucose transporters) or HXT (hexose transporters) family of twelve-transmembrane domain glucose transporters in mammals and yeast, respectively. These proteins are conserved from yeast to humans, and multiple transporters—each with distinct kinetic properties—compete for plasma membrane occupancy in order to enhance or limit the rate of glucose uptake. During growth in the presence of alternative carbon sources, glucose transporters are removed and replaced with the appropriate transporter to help support growth in response to this environment. New insights into the regulated protein trafficking of these transporters reveal the requirement for specific α-arrestins, a little-studied class of protein trafficking adaptor. A defining feature of the α-arrestins is that each contains PY-motifs, which can bind to the ubiquitin ligases from the NEDD4/Rsp5 (Neural precursor cell Expressed, Developmentally Down-regulated 4 and Reverses Spt- Phenotype 5, respectively) family. Specific association of α-arrestins with glucose and carbohydrate transporters is thought to bring the ubiquitin ligase in close proximity to its membrane substrate, and thereby allows the membrane cargo to become ubiquitinated. This ubiquitination in turn serves as a mark to stimulate endocytosis. Recent results show that AMPK phosphorylation of the α-arrestins impacts their abundance and/or ability to stimulate carbohydrate transporter endocytosis. Indeed, AMPK or glucose limitation also controls α-arrestin gene expression, adding an additional layer of complexity to this regulation. Here, we review the recent studies that have expanded the role of AMPK in cellular metabolism to include regulation of α-arrestin-mediated trafficking of transporters and show that this mechanism of regulation is conserved over the ~150 million years of evolution that separate yeast from man.

Properties of 1-phosphofructokinase from Pseudomonas piutida

1977 ◽  
Vol 23 (6) ◽  
pp. 721-725 ◽  
Author(s):  
Sookie S. Bang ◽  
Paul Baumann ◽  
Mark H. Sawyer
Keyword(s):  
Pseudomonas Putida ◽  
Adenosine Triphosphate ◽  
Column Chromatography ◽  
Inhibitory Activity ◽  
Reaction Rate ◽  
Adenosine Monophosphate ◽  
The Other ◽  
Kinetic Properties ◽  
Sephadex Column ◽  
Sigmoidal Kinetics

The 1-phosphofructokinase (1-PFK, EC 2.7.1.56) from Pseudomonas putida was partially purified by a combination of (NH4)2SO4 fractionation and DEAE-Sephadex column chromatography. In its kinetic properties, this enzyme resembled the 1-PFK's from other bacteria. With the substrates fructose-1-phosphate (F-1-P) and adenosine triphosphate (ATP) Michaelis–Menten kinetics were observed, the Km for one substrate being unaffected by a variation in the concentration of the other substrate. At pH 8.0, the Km values for F-1-P and ATP were 1.64 × 10−4 M and 4.08 × 10−4 M, respectively. At fixed concentrations of F-1-P and ATP, an increase in the Mg2+ resulted in sigmoidal kinetics. Activity was inhibited by ATP when the ratio of ATP:Mg2+ was greater than 0.5 suggesting that ATP:2 Mg2+ was the substrate and free ATP was inhibitory. Activity of 1-PFK was stimulated by K+ and to a lesser extent by NH4+ and Na+. The reaction rate was unaffected by 2 mM K2HPO4, pyruvate, phosphoenolpyruvate, adenosine monophosphate, adenosine 3′,5′-cyclic monophosphate, fructose-6-phosphate, glucose-6-phosphate, 6-phosphogluconate, 2-keto-3-deoxy-6-phosphogluconate, or citrate. The results indicated that the 1-PFK from P. putida was not allosterically regulated by a number of metabolites which may play an important role in the catabolism of D-fructose.

Kinetic properties of glutamate dehydrogenase from the gills of Arapaima gigas and Osteoglossum bicirrhosum

1978 ◽  
Vol 56 (4) ◽  
pp. 809-813 ◽  
Author(s):  
J. H. A. Fields ◽  
W. R. Driedzic ◽  
C. J. French ◽  
P. W. Hochachka
Keyword(s):  
Glutamate Dehydrogenase ◽  
Nicotinamide Adenine Dinucleotide ◽  
Energy Charge ◽  
Adenosine Monophosphate ◽  
Adenosine Diphosphate ◽  
Nicotinamide Adenine ◽  
Kinetic Properties ◽  
Guanosine Diphosphate ◽  
Arapaima Gigas ◽  
Reduced Nicotinamide Adenine Dinucleotide

Glutamate dehydrogenase was isolated from the gills of Arapaima gigas and Osteoglossum bicirrhosum and kinetically characterized, in order to determine whether there was any alteration in the ability of the gills to generate ammonia associated with the development of an air-breathing life-style. The catalytic and regulatory properties of both enzymes were found to be very similar. They were activated by leucine, adenosine monophosphate, and adenosine diphosphate, and inhibited by guanosine triphosphate, guanosine diphosphate, and adenosine triphosphate. Inhibition by nicotinamide adenine dinucleotide and reduced nicotinamide adenine dinucleotide was strong in both cases. It was concluded that both enzymes were regulated by a combination of the energy charge of the cell and the redox potential. There is no evidence for any qualitative alteration of the gills to produce ammonia from amino acids in the air breather, Arapaima gigas, as compared with the water breather, Osteoglossum bicirrhosum.

Adenylate kinases of thermophiles Aquifex aeolicus and Geobacillus stearothermophilus: biochemical and kinetic studies

2021 ◽  
pp. 1-9
Author(s):  
Agnieszka Ludwiczak ◽  
Magdalena Wujak ◽  
Anna Kozakiewicz ◽  
Andrzej Wojtczak ◽  
Michał Komoszyński
Keyword(s):  
Atp Synthesis ◽  
Kinetic Studies ◽  
Adenosine Monophosphate ◽  
Adenosine Diphosphate ◽  
Kinetic Properties ◽  
Geobacillus Stearothermophilus ◽  
Aquifex Aeolicus ◽  
Adenylate Kinases ◽  
Activity Of Enzymes ◽  
First Time

Adenylate kinases (AK) play a pivotal role in the regulation of cellular energy. The aim of our work was to achieve the overproduction and purification of AKs from two groups of bacteria and to determine, for the first time, the comprehensive biochemical and kinetic properties of adenylate kinase from Gram-negative Aquifex aeolicus (AKaq) and Gram-positive Geobacillus stearothermophilus (AKst). Therefore we determined KM and Vmax values, and the effects of temperature, pH, metal ions, donors of the phosphate groups and inhibitor Ap5A for both thermophilic AKs. The kinetic studies indicate that both AKs exhibit significantly higher affinity for substrates with the pyrophosphate group than for adenosine monophosphate. AK activation by Mg2+ and Mn2+ revealed that both ions are efficient in the synthesis of adenosine diphosphate and adenosine triphosphate; however, Mn2+ ions at 0.2–2.0 mmol/L concentration were more efficient in the activation of the ATP synthesis than Mg2+ ions. Our research demonstrates that zinc ions inhibit the activity of enzymes in both directions, while Ap5A at a concentration of 10 µmol/L and 50 µmol/L inhibited both enzymes with a different efficiency. Sigmoid-like kinetics were detected at high ATP concentrations not balanced by Mg2+, suggesting the allosteric effect of ATP for both bacterial AKs.

Fructose diphosphatase from rabbit liver. X. Isolation and kinetic properties of the enzyme-adenosine monophosphate complex

Biochemistry ◽  
1968 ◽  
Vol 7 (10) ◽  
pp. 3628-3633 ◽  
Author(s):  
Sandro. Pontremoli ◽  
Enrico. Grazi ◽  
Augusto. Accorsi
Keyword(s):  
Adenosine Monophosphate ◽  
Rabbit Liver ◽  
Kinetic Properties
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