scholarly journals The equilibrium constant of the isocitrate dehydrogenase reaction

1968 ◽  
Vol 110 (2) ◽  
pp. 217-222 ◽  
Author(s):  
J. C. Londesborough ◽  
K. Dalziel
Keyword(s):  
Ionic Strength ◽  
Equilibrium Constant ◽  
Isocitrate Dehydrogenase ◽  
Ion Concentration ◽  
Oxidative Decarboxylation ◽  
Heat Of Reaction ◽  
Dehydrogenase Reaction

1. The equilibrium constant for oxidative decarboxylation of isocitrate by NADP+, catalysed by isocitrate dehydrogenase, was measured in solutions of various ionic strengths and at several temperatures. 2. Thermodynamic values for the reaction were obtained by extrapolation to zero ionic strength, and the heat of reaction was estimated. 3. The effect of Mg2+ ion concentration on the equilibrium was studied.

scholarly journals The nature of carbon dioxide substrate and equilibrium constant of the 6-phosphogluconate dehydrogenase reaction

1969 ◽  
Vol 115 (4) ◽  
pp. 633-638 ◽  
Author(s):  
R. H. Villet ◽  
K. Dalziel
Keyword(s):  
Carbon Dioxide ◽  
Free Energy ◽  
Equilibrium Constant ◽  
Heat Of Reaction ◽  
Phosphogluconate Dehydrogenase ◽  
Sheep Liver ◽  
Dehydrogenase Reaction ◽  
Reductive Carboxylation ◽  
Primary Substrate

1. It was shown that dissolved CO2 and not HCO3− or H2CO3 is the primary substrate for reductive carboxylation with 6-phosphogluconate dehydrogenase from sheep liver. 2. The equilibrium constant of the reaction was measured in solutions of various ionic strengths and at several temperatures, and the free energy and heat of reaction were determined.

Residual phase lignin in haft cooking related to the conditions in the cook

1997 ◽  
Vol 12 (4) ◽  
pp. 225-229
Author(s):  
Cart-in A-S. Gustavsson ◽  
Chritofer T. Lindgren ◽  
Mikael E. Lindström
Keyword(s):  
Hydrogen Sulfide ◽  
Ionic Strength ◽  
Sodium Ion ◽  
Ion Concentration ◽  
Constant Composition ◽  
Hydroxide Ion ◽  
Sulfide Ion ◽  
Residual Phase ◽  
Kraft Cooking ◽  
Very High

Abstract The amount of lignin reacting according to the slow residual phase, i.e. the residual phase lignin, is in many perspectives an interesting issue. The purpose of the present investigation was to develop a mathematical model to show how the amount of residual phase lignin in the kraft cooking of spruce chips (Picm ahies) depends on the conditions in the earlier phases of the cook. The variables studied were hydroxide ion concentration, hydrogen sulfide ion concentration and ionic strength. The liquor-to-wood ratio during pulping was very high to maintain approximately constant chemical concentrations throughout each experiment (so called "constant composition" cooks). An increase in hydroxide ion concentration andtor hydrogen sulfide ion concentration leads to a decrease in the amount of residual phase lignin, while an increase in ionic strength, i.e. sodium ion concentration, leads to an increase. A signiticant result is that the hydrogen sulfide ion concentration has a pronounced influence on the amount of residual phase lignin during a cook at a low hydroxide ion concentration. The amount of residual phase lignin expressed as % lignin on wood, L,, can be described by the following equation developed for "constant composition" cooks (when cooking with a constant sodium ion concentration of 2 mol/L): LT=0,55-0.32*[HO-](-1,3)*ln[HS-] This equation is valid for a concentration of HO- in the range from 0.17 to 1.4, and a hydrogen sulfide ion concentration from 0.07 to 0.6 mol/L.

SOME EQUILIBRIUM CONSTANTS OF TRANSITION METAL HALIDES

1960 ◽  
Vol 38 (10) ◽  
pp. 1827-1836 ◽  
Author(s):  
M. W. Lister ◽  
P. Rosenblum
Keyword(s):  
Ionic Strength ◽  
Transition Metal ◽  
Equilibrium Constant ◽  
Spectrophotometric Method ◽  
Equilibrium Constants ◽  
Cell Voltage ◽  
Metal Halides ◽  
Complex Ions ◽  
Anomalous Variation ◽  
A Cell

Measurements are reported on the formation of complex ions in solutions containing cupric and chloride or bromide ions, and solutions of nickel or cobalt with chloride. In each case the halide was present in very low amount. With copper a spectrophotometric method was used, and a cell voltage method with nickel and cobalt. The ionic strength was kept constant, but the temperature was varied. The data show difficulties of interpretation if it is assumed that only MX+ ions (M is the metal, X is the halogen) are formed, the difficulties arising from the anomalous variation of the equilibrium constant with temperature, and from the general drift of the calculated constants from the e.m.f. measurements. Various explanations are considered and it is shown that postulation of M2X+3 ions is at least a possible explanation.

scholarly journals Immobilization of Isocitrate Dehydrogenase on Mesoporous Silica Foam for Carbon Dioxide Capture

2019 ◽  
Vol 93 ◽  
pp. 04001
Author(s):  
Shunxiang Xia ◽  
Laibao Zhang ◽  
Enjelia Veony
Keyword(s):  
Enzyme Activity ◽  
Mesoporous Silica ◽  
Isocitrate Dehydrogenase ◽  
Carbon Capture ◽  
Large Scale ◽  
Enzyme Stability ◽  
Environmental Parameters ◽  
Capture Process ◽  
Dehydrogenase Reaction ◽  
Improved Stability

Carbon capture can be realized effectively through isocitrate dehydrogenase reaction and the reaction rate was strongly affected by the environmental parameters such as pH and temperature. Enzyme immobilization was conducted to improve the enzyme stability during the capture process. By simply adsorbing enzyme on the surface of mesoporous silica foam, enzyme stability against temperature, pH and shear stress was improved. The immobilization process can be completed in 5 mins, and 0.87 U enzyme activity was kept for each gram of immobilization material. After 10 cycles, more than 50 percent of enzyme activity remained. The reusability and improved stability made immobilized ICDH a better candidate for large-scale application of carbon capture.

scholarly journals Equilibrium binding of coenzymes and substrates to nicotinamide-adenine dinucleotide phosphate-linked isocitrate dehydrogenase from bovine heart mitochondria

1978 ◽  
Vol 171 (3) ◽  
pp. 733-742 ◽  
Author(s):  
C H Reynolds ◽  
P W Kuchel ◽  
K Dalziel
Keyword(s):  
Ionic Strength ◽  
Isocitrate Dehydrogenase ◽  
Binding Capacity ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Kinetic Properties ◽  
Protein Fluorescence ◽  
Fluorescence Measurements ◽  
Equilibrium Binding ◽  
Maximum Binding Capacity ◽  
Fluorescence Titrations

1. The stoicheiometries and affinities of ligand binding to isocitrate dehydrogenase were studied at pH 7.0, mainly by measuring changes in NADPH and protein fluorescence. 2. The affinity of the enzyme for NADPH is about 100-fold greater than it is for NADP+ in various buffer/salt solutions, and the affinities for both coenzymes are decreased by Mg2+, phosphate and increase in ionic strength. 3. The maximum binding capacity of the dimeric enzyme for NADPH, from coenzyme fluorescence and protein-fluorescence measurements, and also for NADP+, by ultrafiltration, is 2 mol/mol of enzyme. Protein-fluorescence titrations of the enzyme with NADP+ are apparently inconsistent with this conclusion, indicating that the increase in protein fluorescence caused by NADP+ binding is not proportional to fractional saturation of the binding sites. 4. Changes in protein fluorescence caused by changes in ionic strength and by the binding of substrates, Mg2+ or NADP+ (but not NADPH) are relatively slow, suggesting conformation changes. 5. In the presence of Mg2+, the enzyme binds isocitrate very strongly, and 2-oxoglutarate rather weakly. 6. Evidence is presented for the formation of an abortive complex of enzyme-Mg2+-isocitrate-NADPH in which isocitrate and NADPH are bound much more weakly than in their complexes with enzyme and Mg2+ alone. 7. The results are discussed in relation to the interpretation of the kinetic properties of the enzyme and its behaviour in the mitochondrion.

scholarly journals Hepatic Transcriptomics Reveals that Lipogenesis Is a Key Signaling Pathway in Isocitrate Dehydrogenase 2 Deficient Mice

Genes ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 728
Author(s):  
Jeong Hoon Pan ◽  
Jingsi Tang ◽  
Mersady C. Redding ◽  
Kaleigh E. Beane ◽  
Cara L. Conner ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Isocitrate Dehydrogenase ◽  
De Novo ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Tca Cycle ◽  
De Novo Lipogenesis ◽  
Oxidative Decarboxylation ◽  
Qpcr Analysis ◽  
Isocitrate Dehydrogenase 2 ◽  
Mice Liver

Mitochondrial nicotinamide adenine dinucleotide phosphate (NADP+)-dependent isocitrate dehydrogenase (IDH2) plays a key role in the intermediary metabolism and energy production via catalysing oxidative decarboxylation of isocitrate to α-ketoglutarate in the tricarboxylic acid (TCA) cycle. Despite studies reporting potential interlinks between IDH2 and various diseases, there is lack of effort to comprehensively characterize signature(s) of IDH2 knockout (IDH2 KO) mice. A total of 6583 transcripts were identified from both wild-type (WT) and IDH2 KO mice liver tissues. Afterwards, 167 differentially expressed genes in the IDH2 KO group were short-listed compared to the WT group based on our criteria. The online bioinformatic analyses indicated that lipid metabolism is the most significantly influenced metabolic process in IDH2 KO mice. Moreover, the TR/RXR activation pathway was predicted as the top canonical pathway significantly affected by IDH2 KO. The key transcripts found in the bioinformatic analyses were validated by qPCR analysis, corresponding to the transcriptomics results. Further, an additional qPCR analysis confirmed that IDH2 KO caused a decrease in hepatic de novo lipogenesis via the activation of the fatty acid β-oxidation process. Our unbiased transcriptomics approach and validation experiments suggested that IDH2 might play a key role in homeostasis of lipid metabolism.

On the influence of ionic strength on the equilibrium constant of copper-murexide interaction

Talanta ◽  
1990 ◽  
Vol 37 (11) ◽  
pp. 1107-1108 ◽  
Author(s):  
F FAMOORI ◽  
S HAGHGOO ◽  
M SHAMSIPUR
Keyword(s):  
Ionic Strength ◽  
Equilibrium Constant

Interaction between effects of low pH and low ion concentration on mortality during early development of medaka, Oryzias latipes

1989 ◽  
Vol 67 (9) ◽  
pp. 2158-2168 ◽  
Author(s):  
Weerawan Chulakasem ◽  
Jay A. Nelson ◽  
John J. Magnuson
Keyword(s):  
Ionic Strength ◽  
Oryzias Latipes ◽  
Calcium Content ◽  
Explanatory Models ◽  
Low Ph ◽  
Ion Concentration ◽  
Physiological Mechanisms ◽  
Effects Of Ph ◽  
Independent Effects ◽  
Patterns Of Interaction

Eggs and fry of medaka, Oryzias latipes, were incubated continuously from shortly after fertilization until 7 days after hatching using a factorial design with four water conductivities (9, 16, 28, and 49 μS/cm) and four pH levels (4.2, 4.5, 5.6, or 6.6). Results on survival suggest that only during hatching can independent effects of pH and ionic strength be statistically separated. Mortalities of encapsulated embryos and fry were determined by interactions between pH and ionic strength. Sensitivity to dilute, low pH water was greatest in freshly fertilized eggs and 1- to 4-day-old fry. Egg mortality occurred within a day after water hardening, whereas fry mortality occurred more gradually over the 3 days following hatching. Dilute, low pH water did not influence oxygen consumption or calcium content of eggs, yet impeded normal developmental increases in both calcium content and metabolic rate in fry. Results are discussed mechanistically with respect to causes of the mortality, and two explanatory models are proposed. Speculation that patterns of interaction in multivariate analyses can be indicative of physiological mechanisms also is entertained.

Mechanistic Information from the Effect of Pressure on the Kinetics of Hydrolysis of Iodopentaaquochromium(III) Ion

1975 ◽  
Vol 53 (24) ◽  
pp. 3697-3701 ◽  
Author(s):  
Milton Cornelius Weekes ◽  
Thomas Wilson Swaddle
Keyword(s):  
Ionic Strength ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Kinetics Of Hydrolysis ◽  
Rate Of Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Aqueous Hclo ◽  
Conjugate Base

The rate of hydrolysis of iodopentaaquochromium(III) ion has been measured as a function of pressure (0.1 to 250 MPa) and hydrogen ion concentration (0.1 to 1.0 mol kg−1) at 298.2 K and ionic strength 1.0 mol kg−1 (aqueous HClO4–LiClO4). The volumes of activation for the acid independent and inversely acid dependent hydrolysis pathways are −5.4 ± 0.5 and −1.6 ± 0.3 cm3 mol−1 respectively, and are not detectably pressure-dependent. Consideration of these values, together with the molar volume change of −3.3 ± 0.3 cm3 mol−1 determined dilatometrically for the completed hydrolysis reaction, indicates that the mechanisms of the two pathways are associative interchange (Ia) and dissociative conjugate base (Dcb) respectively.

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