scholarly journals The Ca2+-transporting ATPases of rabbit and trout exhibit different pH- and temperature-dependences

1993 ◽  
Vol 293 (2) ◽  
pp. 469-473 ◽  
Author(s):  
E N Chini ◽  
F G de Toledo ◽  
M C Albuquerque ◽  
L de Meis
Keyword(s):  
Temperature Dependence ◽  
Atp Hydrolysis ◽  
Ph Dependence ◽  
Atp Synthesis ◽  
Amino Acid Residues ◽  
Specific Amino Acid ◽  
Temperature Dependences ◽  
Temperature Ranges ◽  
Similar Temperature ◽  
Membrane Bound

The phosphorylation of the trout sarcoplasmic-reticulum Ca(2+)-ATPase by Pi differs in its temperature- and pH-dependence from the rabbit ATPase. In the trout enzyme, the apparent affinity for Pi and maximum phosphoenzyme values do not vary over a pH and temperature ranges that have a pronounced effect on the rabbit enzyme. The lack of temperature-dependence for phosphorylation is observed at pH 6.8. At pH 8.0, the temperature profile for phosphorylation of the trout enzyme resembles that of the rabbit at pH 6.8. The rabbit ATPase is no longer phosphorylated by Pi after solubilization with the detergent C12E9. In contrast, the trout enzyme can be phosphorylated by Pi after solubilization with C12E9, and the same levels of phosphoenzyme were obtained with the soluble and membrane-bound ATPase at both 0 degrees and 25 degrees C. In the range of 0-20 degrees C, the rates of ATP synthesis and of Ca2+ uptake by the trout ATPase are less temperature-dependent than for the rabbit enzyme. However, both isoenzymes catalyse ATP hydrolysis with similar temperature-dependences. The results raise the possibility that protonation of specific amino acid residues may contribute to the lack of temperature-dependence for phosphorylation of the trout Ca(2+)-ATPase.

TEMPERATURE DEPENDENCE OF ATP HYDROLYSIS BY LOACH EMBRYONIC CELLS Na+/K+-ATPase UNDER THE INFLUENCE OF He-Ne LASER

2016 ◽  
Vol 18 (2) ◽  
pp. 88-93
Author(s):  
M. S. Romaniuk ◽  
◽  
S. M. Mandzynets ◽  
M. V. Bura ◽  
D. I. Sanagursky ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Atp Hydrolysis ◽  
Embryonic Cells

Studies on the Temperature Stability of Pure and Doped Triglycine Sulphate Crystals Using TGA/DTA

2020 ◽  
Vol 10 (3) ◽  
pp. 206-212
Author(s):  
Vijeesh Padmanabhan ◽  
Maneesha P. Madhu ◽  
Supriya M. Hariharan
Keyword(s):  
Thermal Analysis ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Temperature Stability ◽  
Bandgap Energy ◽  
Dsc Analysis ◽  
Slow Cooling ◽  
As Doping ◽  
Similar Dependence ◽  
Temperature Ranges

Aim: To study the temperature stability of TGS doped with ZnSO4, CdCl2, BaCl2, and compare it with that of pure TGS. Objectives: Synthesizing pure and doped TGS and studying their temperature dependence using TGA, DTA, and DSC analysis. Methods: Slow cooling solution growth was used to grow single crystals of pure and doped TGS. The TGA, DTA and DSC analysis was conducted for determining the temperature stability. Results: The thermal analysis of pure and doped TGS shows that the doped samples show a similar dependence on temperature as pure TGS. The temperature of decomposition of pure and doped samples (BTGS, ZTGS, CdTGS) was 226.60°C, 228.38°C, 229.13°C, and 239.13°C respectively. The melting onset of these samples was 214.51°C, 216.04°C, 217.69°C and 216.04°C respectively. Conclusion: The study shows that doping TGS with the above three described materials did not alter their temperature stability considerably. It is a good result as doping TGS, for varying its characteristics like absorbance, reflectance, bandgap energy, etc., which did not alter its temperature stability. Therefore, TGS doped with the above three dopants can be used at the same temperature ranges as of pure TGS but with much-improved efficiency.

Temperature Dependences in the O + OH → O2 + H Reaction. Quasiclassical Trajectory Calculation

1993 ◽  
Vol 58 (2) ◽  
pp. 234-243 ◽  
Author(s):  
Viliam Klimo ◽  
Martina Bittererová ◽  
Stanislav Biskupič ◽  
Ján Urban ◽  
Miroslav Micov
Keyword(s):  
Temperature Dependence ◽  
Energy Surface ◽  
Analytical Form ◽  
Mean Values ◽  
Quantum Numbers ◽  
Mean Lifetime ◽  
Temperature Dependences ◽  
Quasiclassical Trajectory Calculation ◽  
The Mean ◽  
Combustion Processes

The reaction O + OH → O2 + H in conditions of combustion of hydrocarbons and polymers was modelled by using the method of quasiclassical trajectories. The potential energy surface was determined by the multiconfiguration interaction method and fitted with the analytical form of the extended LEPS function. Attention was paid to the mean values of the vibrational and rotational quantum numbers of O2 molecules and their temperature dependence. The temperature dependence of the mean lifetime of the OOH collision complex was also examined. The calculated rate constants were analyzed and compared with the experimental data over the temperature region of the combustion processes.

The Urbach Rule for the Sodium- and Potassium-Halides

1974 ◽  
Vol 29 (1) ◽  
pp. 145-157 ◽  
Author(s):  
Tetsuhiko Tomiki ◽  
Takeo Miyata ◽  
Hirokazu Tsukamoto
Keyword(s):  
Temperature Dependence ◽  
Acoustic Phonon ◽  
Frequency Factor ◽  
Host Lattice ◽  
Exciton Peak ◽  
Urbach Rule ◽  
Temperature Dependences ◽  
Hole Band ◽  
Sodium And Potassium ◽  
Potassium Halides

Phenomenological and physical aspects of the intrinsic tail spectra of the alkalihalides are studied referring to the new results on the intrinsic tail spectra of KBr and KI and to the temperature dependences of the lowest-energy Γ-exciton peak of the sodium- and potassium-halides. Systematically analysing the temperature dependence of the steepness parameter σs (T) of the Urbach rule for these halides, it is found that the frequency factor has the value nearly equal to the acoustic phonon energy at X or L of each host lattice and the steepness constant σs0 becomes larger in passing from fluoride to iodide. This halogen dependence of σs0 is discussed in terms of the hole band-mass of the Γ8-level.

scholarly journals The role of enzyme dynamics and tunnelling in catalysing hydride transfer: studies of distal mutants of dihydrofolate reductase

2006 ◽  
Vol 361 (1472) ◽  
pp. 1307-1315 ◽  
Author(s):  
Lin Wang ◽  
Nina M Goodey ◽  
Stephen J Benkovic ◽  
Amnon Kohen
Keyword(s):  
Temperature Dependence ◽  
Dihydrofolate Reductase ◽  
Isotope Effects ◽  
Hydride Transfer ◽  
Activation Parameters ◽  
Physical Nature ◽  
Enzyme Dynamics ◽  
Temperature Dependences ◽  
Donor Acceptor ◽  
Significant Temperature

Residues M42 and G121 of Escherichia coli dihydrofolate reductase ( ec DHFR) are on opposite sides of the catalytic centre (15 and 19 Å away from it, respectively). Theoretical studies have suggested that these distal residues might be part of a dynamics network coupled to the reaction catalysed at the active site. The ec DHFR mutant G121V has been extensively studied and appeared to have a significant effect on rate, but only a mild effect on the nature of H-transfer. The present work examines the effect of M42W on the physical nature of the catalysed hydride transfer step. Intrinsic kinetic isotope effects (KIEs), their temperature dependence and activation parameters were studied. The findings presented here are in accordance with the environmentally coupled hydrogen tunnelling. In contrast to the wild-type (WT), fluctuations of the donor–acceptor distance were required, leading to a significant temperature dependence of KIEs and deflated intercepts. A comparison of M42W and G121V to the WT enzyme revealed that the reduced rates, the inflated primary KIEs and their temperature dependences resulted from an imperfect potential surface pre-arrangement relative to the WT enzyme. Apparently, the coupling of the enzyme's dynamics to the reaction coordinate was altered by the mutation, supporting the models in which dynamics of the whole protein is coupled to its catalysed chemistry.

scholarly journals Aerobic Growth of Escherichia coli Is Reduced, and ATP Synthesis Is Selectively Inhibited when Five C-terminal Residues Are Deleted from the ϵ Subunit of ATP Synthase

2015 ◽  
Vol 290 (34) ◽  
pp. 21032-21041 ◽  
Author(s):  
Naman B. Shah ◽  
Thomas M. Duncan
Keyword(s):  
Escherichia Coli ◽  
Atp Synthase ◽  
Atp Hydrolysis ◽  
Atp Synthesis ◽  
Intrinsic Rate ◽  
Synthesis Rate ◽  
Final Segment ◽  
Rotary Catalysis

F-type ATP synthases are rotary nanomotor enzymes involved in cellular energy metabolism in eukaryotes and eubacteria. The ATP synthase from Gram-positive and -negative model bacteria can be autoinhibited by the C-terminal domain of its ϵ subunit (ϵCTD), but the importance of ϵ inhibition in vivo is unclear. Functional rotation is thought to be blocked by insertion of the latter half of the ϵCTD into the central cavity of the catalytic complex (F1). In the inhibited state of the Escherichia coli enzyme, the final segment of ϵCTD is deeply buried but has few specific interactions with other subunits. This region of the ϵCTD is variable or absent in other bacteria that exhibit strong ϵ-inhibition in vitro. Here, genetically deleting the last five residues of the ϵCTD (ϵΔ5) caused a greater defect in respiratory growth than did the complete absence of the ϵCTD. Isolated membranes with ϵΔ5 generated proton-motive force by respiration as effectively as with wild-type ϵ but showed a nearly 3-fold decrease in ATP synthesis rate. In contrast, the ϵΔ5 truncation did not change the intrinsic rate of ATP hydrolysis with membranes. Further, the ϵΔ5 subunit retained high affinity for isolated F1 but reduced the maximal inhibition of F1-ATPase by ϵ from >90% to ∼20%. The results suggest that the ϵCTD has distinct regulatory interactions with F1 when rotary catalysis operates in opposite directions for the hydrolysis or synthesis of ATP.

scholarly journals Purification and Biochemical Characterization of the F1Fo-ATP Synthase from Thermoalkaliphilic Bacillus sp. Strain TA2.A1

2003 ◽  
Vol 185 (15) ◽  
pp. 4442-4449 ◽  
Author(s):  
Gregory M. Cook ◽  
Stefanie Keis ◽  
Hugh W. Morgan ◽  
Christoph von Ballmoos ◽  
Ulrich Matthey ◽  
...  
Keyword(s):  
Atp Synthase ◽  
Biochemical Characterization ◽  
Atp Hydrolysis ◽  
Sodium Dodecyl ◽  
Electrical Potential ◽  
Atp Synthesis ◽  
Intrinsic Property ◽  
Protein Sequencing ◽  
Hydrolysis Activity

ABSTRACT We describe here purification and biochemical characterization of the F1Fo-ATP synthase from the thermoalkaliphilic organism Bacillus sp. strain TA2.A1. The purified enzyme produced the typical subunit pattern of an F1Fo-ATP synthase on a sodium dodecyl sulfate-polyacrylamide gel, with F1 subunits α, β, γ, δ, and ε and Fo subunits a, b, and c. The subunits were identified by N-terminal protein sequencing and mass spectroscopy. A notable feature of the ATP synthase from strain TA2.A1 was its specific blockage in ATP hydrolysis activity. ATPase activity was unmasked by using the detergent lauryldimethylamine oxide (LDAO), which activated ATP hydrolysis >15-fold. This activation was the same for either the F1Fo holoenzyme or the isolated F1 moiety, and therefore latent ATP hydrolysis activity is an intrinsic property of F1. After reconstitution into proteoliposomes, the enzyme catalyzed ATP synthesis driven by an artificially induced transmembrane electrical potential (Δψ). A transmembrane proton gradient or sodium ion gradient in the absence of Δψ was not sufficient to drive ATP synthesis. ATP synthesis was eliminated by the electrogenic protonophore carbonyl cyanide m-chlorophenylhydrazone, while the electroneutral Na+/H+ antiporter monensin had no effect. Neither ATP synthesis nor ATP hydrolysis was stimulated by Na+ ions, suggesting that protons are the coupling ions of the ATP synthase from strain TA2.A1, as documented previously for mesophilic alkaliphilic Bacillus species. The ATP synthase was specifically modified at its c subunits by N,N′-dicyclohexylcarbodiimide, and this modification inhibited ATP synthesis.

Temperature dependence of heats of vaporization, saturated vapour pressures and cohesive energies for a group of amines

1979 ◽  
Vol 44 (12) ◽  
pp. 3521-3528 ◽  
Author(s):  
Vladimír Majer ◽  
Václav Svoboda ◽  
Josef Koubek ◽  
Jiří Pick
Keyword(s):  
Temperature Dependence ◽  
Saturated Vapour ◽  
Temperature Dependences ◽  
Experimental Values ◽  
Cohesive Energies ◽  
Heats Of Vaporization

The temperature dependences of heats of vaporization of propylamine, isopropylamine, butylamine, isobutylamine, sec-butylamine, cyclohexylamine, diethylamine and triethylamine and saturated vapour pressures of butylamine, isobutylamine, sec-butylamine and triethylamine were measured. The cohesive energies of amines studied in dependence on temperature were calculated from the experimental values.

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