Effect of Temperature on Standard Transformed Gibbs Energies of Formation of Reactants at Specified pH and Ionic Strength and Apparent Equilibrium Constants of Biochemical Reactions

2001 ◽  
Vol 105 (32) ◽  
pp. 7865-7870 ◽  
Author(s):  
Robert A. Alberty
Keyword(s):  
Ionic Strength ◽  
Equilibrium Constants ◽  
Effect Of Temperature ◽  
Biochemical Reactions ◽  
Gibbs Energies ◽  
Apparent Equilibrium

Adjustment of K' for the creatine kinase, adenylate kinase and ATP hydrolysis equilibria to varying temperature and ionic strength.

1996 ◽  
Vol 199 (2) ◽  
pp. 509-512 ◽  
Author(s):  
W E Teague ◽  
E M Golding ◽  
G P Dobson
Keyword(s):  
Creatine Kinase ◽  
Ionic Strength ◽  
Adenylate Kinase ◽  
Atp Hydrolysis ◽  
Equilibrium Constants ◽  
Experimental Conditions ◽  
Physiological Conditions ◽  
Free Energy Of Formation ◽  
Apparent Equilibrium ◽  
Energy Of Formation

Comparative physiologists and biochemists working with tissues at varying temperatures and ionic strength are required to adjust apparent equilibrium constants (K') of biochemical reactions to the experimental conditions prior to calculating cytosolic bioenergetic parameters (transformed Gibbs free energy of formation, DeltafG' ATP; cytosolic phosphorylation ratio, [ATP]/[ADP][Pi]; [phosphocreatine]: [orthophosphate] ratio [PCr]/[Pi]) and kinetic parameters (free [ADP], [Pi] and [AMP]). The present study shows how to adjust both K' and the equilibrium constants of reference reactions (Kref) of creatine kinase (ATP: creatine N-phosphotransferase; EC 2.7.3.2), adenylate kinase (ATP:AMP phosphotransferase; EC 2.7.4.3) and adenosinetriphosphatase (ATP phosphohydrolase; EC 3.6.1.3) to temperature and ionic strength. This information, together with our previous study showing how to adjust equilibria to varying pH and pMg, is vital for the quantification of organ and tissue bioenergetics of ectotherms and endotherms under physiological conditions.

Thermodynamics of chelation. II. Iron(II) and zinc(II) complexes of 6-Methylpyridine-2-aldehyde 2'-pyridylhydrazone

1969 ◽  
Vol 22 (11) ◽  
pp. 2333 ◽  
Author(s):  
RW Green ◽  
WG Goodwin
Keyword(s):  
Ionic Strength ◽  
Equilibrium Constants

6-Methylpyridine-2-aldehyde 2?-pyridylhydrazone is a stronger base but weaker ligand than its parent, paphy. Equilibrium constants are reported for seven temperatures from 5� to 60� and over a range of ionic strength. The properties of the ligand are discussed in terms of the derived enthalpies and entropies of reaction.

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.

Gel filtration studies of oxyhemerythrin. II. Effect of temperature and ionic strength on the association-dissociation equilibriums

Biochemistry ◽  
1975 ◽  
Vol 14 (19) ◽  
pp. 4286-4291 ◽  
Author(s):  
Kim Hock Tan ◽  
Steven Keresztes-Nagy ◽  
Allen Frankfater
Keyword(s):  
Ionic Strength ◽  
Gel Filtration ◽  
Effect Of Temperature

A chemical equilibrium modelling strategy for tuning the apparent equilibrium constants of the chemical systems

2019 ◽  
Vol 1049 ◽  
pp. 29-37 ◽  
Author(s):  
Somaiyeh Khodadadi Karimvand ◽  
Marcel Maeder ◽  
Hamid Abdollahi
Keyword(s):  
Chemical Equilibrium ◽  
Equilibrium Constants ◽  
Chemical Systems ◽  
Apparent Equilibrium

Honeybee flight muscle phosphoglucose isomerase: matching enzyme capacities to flux requirements at a near-equilibrium reaction

1997 ◽  
Vol 200 (8) ◽  
pp. 1247-1254 ◽  
Author(s):  
J Staples ◽  
R Suarez
Keyword(s):  
Ionic Strength ◽  
Flight Muscle ◽  
Equilibrium Constants ◽  
Muscle Metabolism ◽  
Phosphoglucose Isomerase ◽  
Glycolytic Flux ◽  
Cell Water ◽  
Economical Design ◽  
Equilibrium Reactions ◽  
Low Ionic Strength

In honeybee flight muscle, there are close matches between physiological flux rates and the maximal activities (Vmax; determined using crude homogenates) of key enzymes catalyzing non-equilibrium reactions in carbohydrate oxidation. In contrast, phosphoglucose isomerase (PGI), which catalyzes a reaction believed to be close to equilibrium, occurs at Vmax values greatly in excess of glycolytic flux rates. In this study, we measure the Vmax of flight muscle PGI, the kinetic parameters of the purified enzyme, the apparent equilibrium constants for the reaction and the tissue concentrations of substrate and product. Using the Haldane equation, we estimate that the forward flux capacity (Vf) for PGI required to achieve physiological glycolytic flux rates is between 800 and 1070 units ml-1 cell water, approximately 45­60 % of the empirically measured Vmax of 1770 units ml-1 cell water at optimal pH (8.0) and low ionic strength (no added KCl). When measured at physiological pH (7.0) and ionic strength (120 mmol l-1 KCl) with saturating levels of substrate, PGI activity is 1130 units ml-1 cell water, a value close to the calculated Vf. These results reveal a very close match between predicted and measured PGI flux capacities, and support the concept of an economical design of muscle metabolism in systems working at very high metabolic rates.

scholarly journals Compositional and Temperature Effects on the Rheological Properties of Polyelectrolyte–Surfactant Hydrogels

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 927 ◽  
Author(s):  
Jiří Smilek ◽  
Sabína Jarábková ◽  
Tomáš Velcer ◽  
Miloslav Pekař
Keyword(s):  
Ionic Strength ◽  
Rheological Properties ◽  
Surfactant Concentration ◽  
Background Electrolyte ◽  
Effect Of Temperature ◽  
Physical Interactions ◽  
Chain Conformations ◽  
Oppositely Charged ◽  
Electrolyte Ph ◽  
Positively Charged

The rheological properties of hydrogels prepared by physical interactions between oppositely charged polyelectrolyte and surfactant in micellar form were studied. Specifically, hyaluronan was employed as a negatively charged polyelectrolyte and Septonex (carbethopendecinium bromide) as a cationic surfactant. Amino-modified dextran was used as a positively charged polyelectrolyte interacting with sodium dodecylsulphate as an anionic surfactant. The effects of the preparation method, surfactant concentration, ionic strength (the concentration of NaCl background electrolyte), pH (buffers), multivalent cations, and elevated temperature on the properties were investigated. The formation of gels required an optimum ionic strength (set by the NaCl solution), ranging from 0.15–0.3 M regardless of the type of hydrogel system and surfactant concentration. The other compositional effects and the effect of temperature were dependent on the polyelectrolyte type or its molecular weight. General differences between the behaviour of hyaluronan-based and cationized dextran-based materials were attributed to differences in the chain conformations of the two biopolymers and in the accessibility of their charged groups.

Effect of temperature on quantifying glycated (glycosylated) hemoglobin by cation-exchange chromatography.

1985 ◽  
Vol 31 (1) ◽  
pp. 114-117 ◽  
Author(s):  
R Flückiger ◽  
T Woodtli
Keyword(s):  
Ionic Strength ◽  
Cation Exchange ◽  
High Performance ◽  
Glycated Hemoglobin ◽  
Operating Temperature ◽  
Glycosylated Hemoglobin ◽  
Regression Line ◽  
Exchange Chromatography ◽  
Effect Of Temperature ◽  
Cation Exchange Chromatography

Abstract As a consequence of nonideal chromatographic conditions, values for stable glycated hemoglobin (HbA1c) determined by cation-exchange chromatography in a commercial minicolumn system (y) or by "high-performance" liquid chromatography (x) differ markedly, yielding the regression line y = 0.82x + 0.6. With use of the protocol specified by the manufacturer, 20% of the HbA1c peak is not collected in the HbA1c fraction. Increasing the ionic strength of the eluting buffer by increasing the operating temperature to 28 degrees C increases the rate of elution from the minicolumn, making results of the two methods more closely comparable (y = 0.98x - 0.22). Because at a given pH the elution volume is determined primarily by the ionic strength, close limits on the composition of the eluting buffer are set by the temperature-dependence of its ionic strength. At a specified temperature and pH the position of a peak can be judged to within a volume of 1 mL if the conductivity of the eluent does not vary by more than +/- 0.05 mS.

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