scholarly journals Thermal inactivation studies of normal and variant human erythrocyte carbonic anhydrases by using a sulphonamide-binding assay

1974 ◽  
Vol 141 (1) ◽  
pp. 219-225 ◽  
Author(s):  
William R. A. Osborne ◽  
Richard E. Tashian
Keyword(s):  
Thermal Inactivation ◽  
Activation Parameters ◽  
Energy Of Activation ◽  
Heat Inactivation ◽  
Activation Entropy ◽  
Carbonic Anhydrases ◽  
Compensating Variation ◽  
Arrhenius Plots ◽  
Heat Stable ◽  
Free Energy Of Activation

Heat-inactivation studies were carried out on the two primary erythrocyte carbonic anhydrase isoenzymes, CA I and CA II, and the secondary isoenzyme of CA I, CA I (+1). In addition, two genetic variants of human isoenzyme CA I, CA Id Michigan (100 Thr→Lys) and CA If London (102 Glu→Lys), and one variant of isoenzyme CA II, CA IIh (251 Asn→Asp), were similarly analysed. The first-order rate constants and Arrhenius plots for these six enzyme forms showed that (1) isoenzyme CA II is more heat-stable than CA I, (2) isoenzyme CA I (+1) is less heat-stable than CA I, (3) the variants CA IIh and CA If London are less heat-stable than the normal enzymes, and (4) isoenzyme CA Id Michigan is more heat-stable than normal CA I. From the values of the slopes of the Arrhenius plots, the energy of activation (Ea) for each isoenzyme and isoenzyme variant was determined, and the following thermodynamic activation parameters were calculated at 55°C: the free energy of activation (ΔG‡), the activation enthalpy (ΔH‡) and the activation entropy (ΔS‡). The ΔG‡ for the enzymes shows a relative constancy with compensating variation in ΔH‡ and ΔS‡. When the values for ΔH‡ are plotted against ΔS‡, an increase in ΔH‡ involves a concomitant increase in ΔS‡.

scholarly journals Effect of heparin on thrombin inactivation by antithrombin-III

1978 ◽  
Vol 173 (3) ◽  
pp. 869-875 ◽  
Author(s):  
R Machovich ◽  
P Arányi
Keyword(s):  
Antithrombin Iii ◽  
Specific Activity ◽  
Activation Parameters ◽  
Heat Inactivation ◽  
Activation Entropy ◽  
First Order ◽  
Heparin Concentration ◽  
First Order Kinetics ◽  
Thermodynamic Activation Parameters ◽  
Time Courses

The inactivation of thrombin by heat and by its physiological inhibitor, antithrombin-III, shows quite different dependence on heparin concentration. Heparin at 250 microgram/ml protects thrombin against heat inactivation, and thrombin behaves heterogeneously in this reaction. In the absence of heparin, the thermodynamic activation parameters change with temperature (deltaH+ = 733 kJ/mol and 210 kJ/mol at 50 and 58 degrees C respectively). When heparin is present, heat inactivation of the protected thrombin species proceeds with deltaH+ = 88 kJ/mol and is independent of temperature in the same range. On the other hand, heparin at 0.125-2.5 microgram/ml accelerates the thrombin-antithrombin-III reaction. Thrombin does not show heterogeneity in this reaction and the time courses at any heparin concentration and any temperature between 0 and 37 degrees C appear to follow first-order kinetics. Activation enthalpy is independent of heparin concentration or temperature, deltaH+ = 82-101 kJ/mol, varying slightly with antithrombin-III concentration and thrombin specific activity. Heparin seems to exert its effect by increasing activation entropy. On the basis of these data we suggest a mechanism of action of heparin in the thrombin-antithrombin-III reaction which accounts for all the important features of the latter and seems to unify the different hypotheses that have been advanced.

scholarly journals Thermal Inactivation of Butyrylcholinesterase in Starch and Gelatin Gels

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 492
Author(s):  
Victoria I. Lonshakova-Mukina ◽  
Elena N. Esimbekova ◽  
Valentina A. Kratasyuk
Keyword(s):  
Thermal Inactivation ◽  
Elevated Temperatures ◽  
Activation Enthalpy ◽  
Activation Parameters ◽  
Simple Approach ◽  
Activation Entropy ◽  
Natural Polymers ◽  
Gelatin Gels ◽  
Starch Gel ◽  
Thermal Stability Of

The present study demonstrates a simple approach to enhancing thermal stability of butyrylcholinesterase (BChE) by using natural polymers. Analysis of thermal inactivation of the tetrameric BChE in starch and gelatin gels at 50–64 °C showed that thermal inactivation followed second-order kinetics and involved two alternating processes of BChE inactivation, which occurred at different rates (fast and slow processes). The activation enthalpy ΔH# and the activation entropy ΔS# for BChE in starch and gelatin gels were evaluated. The values of ΔH# for the fast and the slow thermal inactivation of BChE in starch gel were 61 ± 3, and 22 ± 2 kcal/mol, respectively, and the values of ΔS# were 136 ± 12 and −2.03 ± 0.05 cal∙K−1∙mol−1, respectively. Likewise, the values of ΔH# for BChE in gelatin gel were 58 ± 6 and 109 ± 11 kcal/mol, and the values of ΔS# were 149 ± 16 and 262 ± 21 cal∙K−1∙mol−1, respectively. The values of the activation parameters obtained in this study suggest that starch gel produced a stronger stabilizing effect on BChE exposed to elevated temperatures over long periods compared with gelatin gel.

Viscosity of Dimethyl Sulfoxide + 1,4 Dimethylbenzene System

2008 ◽  
Vol 59 (1) ◽  
pp. 45-48
Author(s):  
Oana Ciocirlan ◽  
Olga Iulian
Keyword(s):  
Free Energy ◽  
Dimethyl Sulfoxide ◽  
Atmospheric Pressure ◽  
Entire Range ◽  
Polynomial Equation ◽  
Energy Of Activation ◽  
Excess Gibbs Free Energy ◽  
Experimental Measurements ◽  
Gibbs Energy Of Activation ◽  
Free Energy Of Activation

This paper reports the viscosities measurements for the binary system dimethyl sulfoxide + 1,4-dimethylbenzene over the entire range of mole fraction at 298.15, 303.15, 313.15 and 323.15 K and atmospheric pressure. The experimental viscosities were correlated with the equations of Grunberg-Nissan, Katti-Chaudhri, Hind, Soliman and McAllister; the adjustable binary parameters have been obtained. The excess Gibbs energy of activation of viscous flow (G*E) has been calculated from the experimental measurements and the results were fitted to Redlich-Kister polynomial equation. The obtained negative excess Gibbs free energy of activation and negative Grunberg-Nissan interaction parameter are discussed in structural and interactional terms.

The crystal structure of ethyl-Z-3-amino-2-benzoyl-2-butenoate and measurement of the barrier to E,Z-isomerization

1980 ◽  
Vol 58 (17) ◽  
pp. 1821-1828 ◽  
Author(s):  
Gary D. Fallon ◽  
Bryan M. Gatehouse ◽  
Allan Pring ◽  
Ian D. Rae ◽  
Josephine A. Weigold
Keyword(s):  
Crystal Structure ◽  
Nuclear Magnetic Resonance ◽  
Hydrogen Bond ◽  
Free Energy ◽  
Magnetic Resonance ◽  
Energy Of Activation ◽  
X Ray ◽  
X Ray Crystallography ◽  
Free Energy Of Activation ◽  
Nuclear Magnetic

Ethyl-3-amino-2-benzoyl-2-butenoate crystallizes from pentane as either the E (mp 82–84 °C) or the Z-isomer (mp 95.5–96.5 °C). The E isomer is less stable, and changes spontaneously into the Z, which bas been identified by X-ray crystallography. The structure is characterised by an N–H/ester CO hydrogen bond and a very long C2—C3 bond (1.39 Å). Nuclear magnetic resonance methods have been used to measure the rate of [Formula: see text] isomerization at several temperatures, leading to the estimate that the free energy of activation at 268 K is 56 ± 8 kJ.

Effect of Heat Processing and Ultrasonication Treatment on Custard Apple Peroxidase Activity and Vitamin C

2017 ◽  
Vol 13 (1) ◽  
Author(s):  
Mugdha P. Dabir ◽  
L. Ananthanarayan
Keyword(s):  
Vitamin C ◽  
Arrhenius Plot ◽  
Enzyme Inactivation ◽  
Heat Processing ◽  
Heat Inactivation ◽  
Ultrasonic Power ◽  
First Order ◽  
Complete Inactivation ◽  
Heat Stable ◽  
Custard Apple

Abstract: Peroxidase isolated from custard apple (Annona squamosa L.) being a heat stable enzyme can be inactivated by heat processing and ultrasonication treatment as well. Heat processing took up to 22 min at 91 °C for complete inactivation of peroxidase. The ultrasonication treatment was performed at 40, 55, 70, 85 and 100 W ultrasonic power and was found to achieve complete inactivation at 85 W as well as at 100 W power within 5 min. The heat inactivation followed first-order reaction kinetics and the activation energy (Ea) calculated from Arrhenius plot was found to be 7.03 × 104 J/mol, which was near the reported range for peroxidases. Heat processing caused 52.7 % loss of vitamin C while achieving complete inactivation of peroxidase at 91 °C for 22 min, whereas ultrasonication caused 21.6 % vitamin C loss at 85 W power within 5 min. Ultrasonication was thus found to be efficient in retaining vitamin C while achieving complete enzyme inactivation.

Heat Stability of the Bile Salt-Stimulated Lipase in Human Milk Fortified with Sodium Taurocholate1

1988 ◽  
Vol 51 (4) ◽  
pp. 310-313 ◽  
Author(s):  
H. L. PAN ◽  
C. W. DILL ◽  
E. S. ALFORD ◽  
S. L. DILL ◽  
C. A. BAILEY ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Human Milk ◽  
Bile Salt ◽  
Lipase Activity ◽  
Sodium Taurocholate ◽  
Heat Stability ◽  
Heat Inactivation ◽  
Temperature Differential ◽  
Heat Stable ◽  
Control Samples

Time-temperature relationships for heat-inactivation of the bile salt-stimulated lipase activity were compared in whole human milk and in the same product fortified to 9 mM/ml with sodium taurocholate. Heat treatments were varied from 45 to 70°C for times ranging from 15s to 40 min. Enzyme activity was more heat stable in human milk fortified with taurocholate than in control samples. The temperature required for the onset of heat inactivation at 30-min holding time was increased from 45°C for control samples to 60°C following addition of taurocholate. A temperature differential of approximately 12°C was required in the fortified milks to produce inactivation equivalent to that observed in the control milks over the heating range studied.

scholarly journals Kinetic Studies on Saponification of Poly(ethylene terephthalate) Waste Powder Using Conductivity Measurements

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Dilip B. Patil ◽  
Vijendra Batra ◽  
Sushil B. Kapoor
Keyword(s):  
Thermodynamic Parameters ◽  
Kinetic Studies ◽  
Frequency Factor ◽  
Reaction Rates ◽  
Reaction Rate Constant ◽  
Activation Entropy ◽  
Constant Frequency ◽  
Free Energy Of Activation ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene

Conductometric measurement technique has been deployed to study the kinetic behavior during the reaction of poly(ethylene terepthalate) (PET) and NaOH. A laboratory made arrangement with facility of continuous stirring was used to carry out experiments at desired temperature. With conductometry, the determination of kinetic as well as thermodynamic parameters becomes more simple and faster as compared to gravimetry. Chemical kinetics of this reaction shows that it is a second order reaction with reaction rate constant 2.88×10-3 g−1 s−1 at 70°C. The specific reaction rates of the saponification reaction in the temperature range at various temperatures (50–80°C) were determined. From the data, thermodynamic parameters such as activation energy, Arrhenius constant (frequency factor), activation enthalpy, activation entropy, and free energy of activation obtained were 54.2 KJ g−1, 5.0×106 min−1, 90.8 KJ g−1, -126.5 JK−1 g−1, and 49.9 KJ g−1, respectively.

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