Authors:Y. Chen, H. Wang, X. Meng, X. Zeng, and J. Xie
A novel thermokinetic research method for determination of the rate constant of a reaction taking place in a batch conduction
calorimeter under isothermal conditions is proposed: the double-thermoanalytical curve method. The method needs only the characteristic
time parameter tm, the peak height Δm at time tm and the peak area a*m after time tm for two thermoanalytical curves measured with different initial concentrations of the reactants: it conveniently calculates
the rate constants. The thermokinetics of four reaction systems were studied with this method, and its validity was verified
by the experimental results.
Authors:Y.-Q. Zhang, X.-C. Zeng, Y. Chen, X.-G. Meng, and A.-M. Tian
On the basis of the theory of thermokinetics proposed in the literature, a novel thermokinetic method for determination of the reaction rate, the characteristic parameter method, is proposed in this paper. Mathematical models were established to determine the kinetic parameters and rate constants. In order to test the validity of this method, the saponifications of ethyl benzoate, ethyl acetate and ethyl propionate, and the formation of hexamethylenetetramine were studied with this method. The rate constants calculated with this method are in agreement with those in the literature, and the characteristic parameter method is therefore believed to be correct.In the light of the characteristic parameter method, we have developed further two thermo-kinetic methods, the thermoanalytical single and multi-curve methods, which are convenient for simultaneous determination of the reaction order and the rate constant. The reaction orders and rate constants of the saponifications of ethyl acetate and ethyl butyrate and the ring-opening reaction of epichlorohydrin with hydrobromic acid were determined with these methods, and their validity was verified by the experimental results.
A novel thermokinetic research method for determination of rate constants of simple-order reaction in batch conduction calorimeter
under isothermal condition, the characteristic parameter method, is proposed in this paper. Only needing the characteristic
time parameter tm obtained from the measured thermoanalytical curve, the kinetic parameters of reactions studied can be calculated
conveniently with this method. The saponifications of ethyl propionate and ethyl acetate in aqueous ethanol solvent, the polymerization
of acrylamide in aqueous solution, the ring opening reaction of epichlorohydrin with hydrobromic acid have been studied. The
experimental results indicate that the characteristic parameter method for simple-order reaction is correct.
Authors:X. Cao, Z. Wang, X. Yang, Y. Liu, and C. Wang
The kinetics of protein thermal transition is of a significant interest from the standpoint of medical treatment. The effect
of sucrose (0–15 mass%) on bovine serum albumin denatured aggregation kinetics at high concentration was studied by the iso-conversional
method and the master plots method using differential scanning calorimetry. The observed aggregation was irreversible and
conformed to the simple order reaction. The denaturation temperature (Tm), the kinetic triplets all increased as the sucrose concentration increased, which indicated the remarkable stabilization
effect of sucrose. The study purpose is to provide new opportunities in exploring aggregation kinetics mechanisms in the presence
Authors:Xiaomin Cao, Yun Tian, Zhiyong Wang, Yuwen Liu, and Cunxin Wang
The kinetics of bovine serum albumin (BSA) denaturation in the absence and the presence of urea was studied by the iso-conversional
method and the master plots method using differential scanning calorimetry (DSC). The observed denaturation process was irreversible
and approximately conformed to the simple order reaction, and the denaturation did not follow rigorously first-order kinetic
model or other integral order reaction models. The denaturation temperature (Tm), apparent activation energy (Ea), approximate order of reaction (n), and pre-exponential factor (A) all distinctly decreased as the 2 mol L−1 urea was added, which indicated that the urea accelerated the denaturation process of BSA and greatly reduced thermal and
kinetic stability of BSA. This study also demonstrated that the iso-conversional method, in combination with the master plots
method, provides a valuable and useful approach to the study of the kinetic process of protein denaturation.
Authors:X. Cao, X. Yang, J. Shi, Y. Liu, and C. Wang
The effect of glucose (0–15 mass%) on the kinetics of bovine serum albumin (BSA) denatured aggregation at high concentration
in aqueous solution has been studied by differential scanning calorimetry. The observed denatured aggregation process was
irreversible and could be characterized by a denaturation temperature (Tm), apparent activation energy (Ea), the approximate order of reaction, and pre-exponential factor (A). As the glucose concentration increased from 0 to 15 mass%, Tm increased, Ea also increased from 514.59409±6.61489 to 548.48611±7.81302 kJ mol−1, and A/s−1 increased from 1.24239E79 to 5.59975E83. The stabilization increased with an increasing concentration of glucose, which was
attributed to its ability to alter protein denatured aggregation kinetics.
The kinetic analysis was carried out using a composite procedure involving the iso-conversional method and the master plots
method. The iso-conversional method indicated that denatured aggregation of BSA in the presence and absence of glucose should
conform to single reaction model. The master plots method suggested that the simple order reaction model best describe the
process. This study shows the combination of iso-conversional method and the master plots method can be used to quantitatively
model the denatured aggregation mechanism of the BSA in the presence and absence of glucose.