Thermokinetics of Liquid-Liquid Reaction of Dy(NO_3)_3 with Histidine

The thermokinetics of liquid liquid reaction of dysprosium nitrate with histidine were studied using a microcalorimeter. On the basis of experimental and calculated results, three thermodynamic parameters (the activation enthalpy, the activation entropy and the activation free energy), the rate constant, three kinetic parameters (the activation energy, the pre exponential constant and the reaction order) were obtained. On the basis of thermodynamics and kinetics, the formation reaction of the complex was discussed.

THE POLYMERIZATION THERMOKINETICS OF PYRROLE IN THE PRESENCE OF IRON TRICHLORIDE

The polymerization thermokinetics of pyrrole in the presence of iron trichloride art studied by using a Calvet microcalorimoter. The apparent activation energy, the pre-exponential constant and reaction order of this reaction in the temperature range of 25.2—37℃ are 34.5 KJ·mol^(-1), 10^(2.74)S^(-1) and 1 respectively. The activation free-energies of this reaction at 25.2°, 30°and 37℃ are 91.8, 92.9 and 94.2 KJ·mol^(-1) respectively.

Studies on Reduced Extent Method for Inhibited Thermokinetics Of Enzyme－Catalyzed Reaction──Inhibition of the laccase－catalyzed oxidation of o－dihydroxybenzene by m－dihydroxybenzene

The thermokinetic reduced extent equations of reversible inhibitions for Michaiels-Menten enzymatic reaction were deduced, and then the criteria for distingushing inhibition type was given and the methods for calculating kinetic parameters, KM,Ki and Urn were suggested. This theory was applied to inverstigate the inhibited thermokinetics of laccase-catalyzed oxidation of o-dihydroxybenzene by m-dihydroxybenzene. The experimental results show the inhibition belongs to reversible competitive type, KM=6.224×10-3 mol L-1, Ki=2. 363 × 10-2 mol. L-1.

MATHEMATICAL MODEL FOR THERMOKINETICS OF IRREVERSIBLE CONSECUTIVE FIRST ORDER REACTIONS

The mathematical model for the thermokinetics of irreversible consecutive first order reactions has been suggested,which was used for the calculation of rate constants and molar enthalpies of the two consecutive steps.And its validity has been verified by the ex- perimental results.

Thermokinetics of the Formation Reaction of Zinc Histidine Complex

The enthalpy change of reaction of zinc chloride with L-α-histidine in thetemperature range of 25-50 ℃ has been determined by a microcalorimeter. On the basis ofexperimental and calculated results, three thermodynamics parameters (the activation enthalpy, theactivation entropy, the activation free energy), the rate constant and three kinetic parameters (theactivation energy, the pre-exponential constant and the reaction order) of the reaction, and thestandard enthalpy of formation of Zn(His)^(2+) (aq.) are obtained. The results showed that the titlereaction easily took place at the studied temperature.

刺槐种子萌发生热曲线的测定及其萌发生长的热动力学研究(英文)

种子的萌发与物质转化和能量交换紧密相关,对种子萌发过程中的热效应进行研究,有助于认识种子的萌发机理及其影响因素。采用武汉大学研制的新型热导式微量量热计测定了刺槐种子的萌发生热曲线。分析了其萌发生热规律与种子萌发生理之间的关系。并根据动力学原理对其生长阶段的热谱进行分析,建立了刺槐萌发生长的动力学模型,25℃ P=208.77/[0.1937+0.8063exp(-0.06563t)]

Thermochemical Kinetics of Sm(Gly)_4Im(ClO_4)_3·2H_2O Reacting with Microbes

The thermochemical kinetics of the rare earth ternary complex Sm(Gly) 4Im(ClO 4) 3·2H 2O (Gly glycine, Im imidazole) reacting with microbes (escherichia coli, bacillus subilis, staphylococcus aureus) was studied by means of Calvet microcalorimeter. The rate constant k of microbe growth was calculated, and the inhibition effect of these complexes to microbes was compared.

A Thermochemical Study on Complex Nickel(Ⅱ) L-α-Histidine

The formation enthalpy of complex nickel(Ⅱ) histidine(His) in water was determined by means of microcalorimetry in the temperature range of 298 15-323 15 K. The standard enthalpy of the formation of Ni(His) 2+ 2(aq) was calculated. On the basis of the experimental and the calculated results, three thermodynamic parameters(the activation enthalpy, the activation entropy and the activation free energy), the rate constants, three kinetic parameters(the apparent activation energy, the pre exponential constant and the reaction order) of the formation reaction of the title complex were obtained.

Microcalorimetric Study on Tyrosine Oxidation Catalyzed by Tyrosinase

Through the method of initial heat release rate, the kinetic property of tyrosine oxidation catalyzed by tyrosinase from Pseudomonas maltophilia was investigated using a LKB-2107 batch microcalorimeter. Tyrosine was catalyzed and oxidized into L-dopa, then into melanin catalyzed by tyrosinase. We found that the tyrosinase reaction obeyed the Michaelis-Menten kinetics, and at 298.15K and pH 7.0, the initial exothermic rate (W0 ) are in the range of 0.1567~0.5704 mJ·s-1, the maximum exothermic rate (Wmax) are in 0.4152 ~ 0.8143mol·L-1, and mean value of the Michaelis constant (Km) is 2.199±0.105104 mol·L-1.

Studies of the Energy Release of Mitochondria from Sporophyte Cytoplasmic Male Sterile Rice by Differential Scanning Calorimetry

The differential scanning calorimetric (DSC)curves of the mitochondria isolated from two varieties of sporophyte cytoplasmic male sterile and their fertile lines of Yie Bai and Ma Xie type rice have been determined. The curves show that the energy is released continuously as temperature rise to 70℃. Some thermodynamic and kinetic parameters of the energy release of the mitochondria have been obtained. The presented results showed that the mitochondria from cytoplasmic male sterile rice released more heat and they had higher energy barrier, less rate, and more complicated mechanism than that of their fertile lines in the energy release process.

A Study of Bacterial Linear Growth Using A Microcalorimetric Method

By using an LKB-2277 bioactivity monitor, we have determined the thermogenesis curves of four kinds of anaerobes linear growth. From the thermogenesis curves, we established the growth thermokinetic equation:dp/dt = km Pn,the order of growth metabolism n=0, and calculated the mean specific rate constant of multiplication μ. It is a new kind of bacterial growth,it was compared with exponential growth.

Thermokinetic Behaviour Degenerated from Limit Cycle Oscillation of Isothermal B-Z Reaction System due to Temperature Controlling of Heat Compensation Type

The thermokinetic behavior of the B-Z reaction system was influenced by both the chemical reaction-heat conduction coupling and the temperature undulation due to temperature controlling of heat compensation type. Quantitative research indicated that this kind of temperature fluctuation will lead to limit cycle degeneration and the periodic or quasi-periodic response behavior of the focus near a supercritical Hopf bifurcation .

Studies on the Reaction Between Laccase and o-methoxyphenol by Microcalorimetry

The reaction between Laccase and o methoxyphenol have been studied by LKB 2107 batch microcalorimetry system. Thermodynamic parameters Δ rH m , Δ G 0 , Δ G ≠ T ,) and kinetic parameters ( K m,k 2 ) have been determined. The process of the reaction has been analyzed from changes in energy by using the transition state theory. Two methods for enhancing catalytic power of Laccase are proposed. The results shown that formation of an enzyme substrate complex is“anticatalytic”. The enter and sole source of catalytic power is the stabilization of transition state; reactant state interactions are by nature inhibitory and only waste catalytic power.

Kinetics of the Action of Na_2SeO_3 on Bacillus subtilis Growth as Studied by Microcalorimetry

Microcalorimetric bioassay for acute cellular toxicity is based on metabolicheat production from cultured cells. The biological response to toxicants is the inhibition of theheat production rate in cells, and toxicity is expressed as the concentration of toxicant that is50% effective to this inhibition (IC_(50)). In this paper, the effect of Na_2SeO_3 on Bacillussubtilis growth was investigated at 37℃ by microcalorimetry. The relationship between growth rateconstants (k) and concentration of Na_2SeO_3(c) shows a logarithmic normal distribution, and IC_(50)is 20.3 μg/mL. All these thermokinetic information is readily obtained by an LKB 2277-204 heatconduction microcalorimeter. Microcalorimetry is a quantitative, inexpensive, and versatile methodfor toxicology research.

Microcalorimetric Study of the Action of Yb^(3+) Ion on the Growth of Staphylococcus aureus

A microcalorimetric method was used to evaluate the action of Yb 3+ ions onthe growth metabolism of Staphylococcus aureus. The power-time curves of the growth metabolism of Staphylococcus aureus and the action of Yb 3+ ions were obtained by using stopped-flow method at 37 ℃. For evaluation of the action, the growth rate constants (k 1 and k 2) for the log phase 1, log phase 2, and the total heat effect (Q total) for Staphylococcus aureus were determined. The results show that Yb 3+ ions at low concentrations have the stimulatory effect on Staphylococcus aureus and that Yb 3+ions at higher concentration could inhibit its growth.

Thermokinetic Study on the Complexation Reaction of the First-Row Transitional Metal Chlorides with Histidine

The enthalpy change of the complexation reactions of the first-row transitional metal chlorides including CrCl3, MnCl2, FeCl2, CoCl2, NiCl2 and CuCl2 with L--histidine in water were determined by a microcalorimeter at 298.15—323.15 K. The standard enthalpy of formation of 32Cr(His)+(aq) and 22M(His)+(aq) (M=Mn, Fe, Co, Ni and Cu) were calculated. Based on the thermodynamic and kinetic equations of the reactions, three thermody-namic parameters (the activation enthalpy, the activation entropy, the activation free energy), the rate constants, and three kinetic parameters (the apparent activation energy, the pre-exponential constant and the reaction order) are obtained. The solid complexes of CrCl3, MnCl2, FeCl2, CoCl2, NiCl2 and CuCl2 with histidine were prepared and identified as Cr(His)2Cl3H2O, Mn(His)2Cl24H2O, Fe(His)2Cl2H2O, Co(His)2Cl2H2O, Ni(His)2Cl2H2O and Cu(His)2Cl2H2O by chemical and elemental analyses. The bonding characteristics of these complexes were char-acterized by IR as well. The results showed that, with the atomic number increasing, three thermodynamic parame-ters, GD!, HD! and SD! of the complexation reaction of these metal chlorides with L-a-histidine in water present an analogy regularity.

Study of Activation and Inhibition of Certain Metal Ions to Amylase Catalyzed Reaction by Microcalorimetry

With or without activation or inhibition of metal ion,the power-time curves of amylase catalyzed reaction were determined by a 2277 thermal activity monitor (Sweden). The Michaelis constant ( K ),apparent Michaelis constant ( K _m),maximum velocity ( v _m) and apparent maximum velocity ( v _ am ) of amylase catalyzed reaction were obtained using thermokinetic theory and reduced extent method. On the basis of data obtained,the following relationships between K _m and concentration of metal ion ( c ) were established: for inhibitor of Ni 2+ K _m=2.9648×10 -3 -1.3912×10 -4 cR =0.9998for inhibitor of Co 2+ K _m=1.0227×10 -3 +8.2676×10 -6 cR =0.9955for activator of Ca 2+ K _m=1.0630×10 -7 c 2-1.8311×10 -6 c +9.3058×10 -6 R =0.9999for activator of Li + K _m=5.6300×10 -8 c 2-1.5329×10 -6 c +1.2662×10 -5 R =0.9999 The K _m- c relationships show a strenuous inhibitory effect for Ni 2+ and a strenuous active effect for Ca 2+ .

Microcalorimetric studies on the dismutation of superoxide anion catalyzed by superoxide dismutase

Thermokinetics of the dismutation of superoxide anion (O ·- 2) catalyzed by superoxide dismutase (SOD), in which the decomposition of hydrogen peroxide catalyzed by catalase is utilized as a source of oxygen and the autoxidation of pyrogallol as a source of the substrate (O ·- 2), has been studied by microcalorimetry. The molar reaction enthalpies of the SOD reaction and the pyrogallol autoxidation have been measured as -160.1 and -218 kJ·mol -1, respectively, at 298.15 K and pH 7.0. A novel method for the determination of SOD activity, the microcalorimetric assay for SOD, has been proposed. The experimental results showed that SOD had no effect on both kinetic parameters and the mechanism for the pyrogallol autoxidation. This autoxidation followed the second_order reaction kinetics in the presence of limited oxygen (the first order with respect to both pyrogallol and O 2), and the second-order rate constants were determined at 298.15 K and pH 8.0 to be 1.25 and 1.30 L·mol -1·s -1 in the absence and presence of SOD, respectively. A possible mechanism for the autoxidation of pyrogallol inhibited by SOD was also suggested.

A double-parameter theoretical model of the conduction calorimeter

A double-parameter theoretical model for the conduction calorimeter, in which the delay of sensing has been considered, is suggested, and a simple method for the determination of the parameters of the model is proposed. The experimental results show that on the basis of this model, the phenomenon of thermogram maximum in thermogram reconstruction can be eliminated, and it can be applied to the thermokinetic investigations of faster thermal change processes.

Thermokinetic Study on the Reversible Competitive Inhibition of Bovine Liver Arginase

A new thermokinetic reduced extent method for studying of the reversible competitive inhibition of single sub-strate enzyme-catalyzed reactions was proposed in this paper. The reaction that arginase-catalyzed hydrolysis of L-arginine to L-ornithine and urea and the inhibition of this reaction by the product, L-ornithine, and exogenous L-lysine were studied at 37 ℃ in 40 mmolL-1 sodium barbiturate-HCl buffer solution (pH=9.4). Michealis con-stant Km for arginine and maximum velocity Vm of the reaction were determined to be 5.14 mmolL-1 and 1.13× 10-2 mmolL-1s-1, respectively. The product inhibition constant KP and inhibitory constant KI of L-lysine were de-termined to be 1.18 and 5.6 mmolL-1, respectively. All the results have better repeatability and self-consistency and are in agreement with literature values. This new method using more direct thermal information from the proc-ess would give more reliable kinetic information than the traditional initial rate method.