Kinetics And Thermodynamic Properties of Trametes Polyzona WRF03 Laccase

Abstract The effect of thermal treatment on the activity of laccase from Trametes polyzona WRF03 was studied at pH and temperature ranges of 3.0 to 6.5 and of 40 to 70 oC respectively. Kinetic data revealed that the heat inactivation of Trametes polyzona WRF03 laccase (TpL) was pH dependent and followed first-order kinetics. There was a positive correlation between activation energy (Ea) for thermal inactivation of TpL and the reaction pH. Highest activation energy, Ea, value of 175.49 kJ/mol was obtained at pH 6.0. On the contrary, the z-value decreased with a lowest value of 12.37 oC at pH 6.0. The high Ea value and low z-value were indicative of the thermo-stable nature of TpL which suggests that pH 6.0 had a compensatory stabilizing effect on TpL against its thermal denaturation. There was a gradual decrease in the enthalpy of denaturation (∆Ho) and Gibb’s free-energy with every 10 % rise in temperature within the investigated pH range, suggesting that TpL was more stable at 40 oC. Positive values of entropy of inactivation (ΔSº) at each temperature indicated that there was no aggregation during the inactivation processes. Thus, these results provided useful information about the behaviour of TpL under certain pH and temperature combination with respect to biotechnological application. Thus, the kinetic and thermodynamic data could be used to design a model to predict the thermal inactivation of TpL during industrial application.

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Temperature and pH effects on the kinetics of 2-aminophenol auto-oxidation in aqueous solution

Open Chemistry ◽

10.2478/bf02476226 ◽

2003 ◽

Vol 1 (3) ◽

pp. 233-241 ◽

Cited By ~ 3

Author(s):

Dumitru Oancea ◽

Mihaela Puiu

Keyword(s):

Experimental Data ◽

Activation Energy ◽

Aqueous Solution ◽

Ph Effects ◽

Influence Of Temperature ◽

First Order ◽

Incremental Methods ◽

First Order Kinetics ◽

Ph Range ◽

Kinetics Of

AbstractThe kinetics of the auto-oxidation of 2-aminophenol (OAP) to 2-amino-phenoxazin-3-one (APX) was followed in air-saturated aqueous solutions and the influence of temperature and pH on the auto-oxidation rate was studied. The kinetic analysis was based on a spectrophotometric method following the increase of the absorbance of APX. The process follows first order kinetics according to the rate law—d[OAP]/dt=k′[OAP]. The experimental data, within the pH range 4–9.85, were analyzed using both differential and incremental methods. The temperature variation of the overall rate constant was studied at pH=9.85 within the range 25–50°C and the corresponding activation energy was evaluated.

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Kinetics of Ascorbic Acid Degradation in Green Asparagus during Heat Processing

Journal of Food Protection ◽

10.4315/0362-028x-61.11.1518 ◽

1998 ◽

Vol 61 (11) ◽

pp. 1518-1521 ◽

Cited By ~ 17

Author(s):

M. J. ESTEVE ◽

A. FRÍGOLA ◽

L. MARTORELL ◽

C. RODRIGO

Keyword(s):

Activation Energy ◽

Ascorbic Acid ◽

Heat Processing ◽

Time Intervals ◽

Ethylene Vinyl Alcohol ◽

First Order ◽

First Order Kinetics ◽

Z Value ◽

Kinetics Of ◽

Green Asparagus

The effect of heating on ascorbic acid in green asparagus during a simulated retort operation was investigated. The asparagus was heated in trays of ethylene-vinyl alcohol copolymer for selected time intervals at four temperatures ranging from 110 to 125°C. It was found that the rate of degradation followed first-order kinetics. Kinetic parameters were obtained by using two least squares methods. The activation energy and z value were 35 kcal/mol and 20°C, respectively.

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Mechanisms of heat inactivation of a proteinase from Pseudomonas fluorescens biotype I

Journal of Dairy Research ◽

10.1017/s002202990002519x ◽

1987 ◽

Vol 54 (1) ◽

pp. 51-60 ◽

Cited By ~ 17

Author(s):

Peter Diermayr ◽

Stefan Kroll ◽

Henning Klostermeyer

Keyword(s):

Pseudomonas Fluorescens ◽

Gel Filtration ◽

Heat Inactivation ◽

Decimal Reduction Time ◽

Reduction Time ◽

First Order ◽

First Order Kinetics ◽

Rapid Inactivation ◽

Temperature Ranges ◽

Two Temperature

SummaryHeat inactivation of a metalloproteinase, isolated from Pseudomonas fluorescens biotype I strain 112, was investigated in the temperature ranges 50–60 °C and 90–140 °C. At 90 °C the denaturation of the enzyme followed first-order kinetics with a decimal reduction time of 110 min and a velocity constant K of 3·5 × 10−4 s−1. Activation energy Ea was 100 kJ/mol for this temperature range. In the 50–60 °C region the proteinase was inactivated by autolysis, as shown by electrophoresis and gel filtration. At 55 °C the decimal reduction time was ∼ 22 s, at 57 °C it was 8 s. Rapid inactivation at 55 °C was only possible if the enzyme was heated from lower temperatures, but not if cooled down from 90 °C. This is due to a conformational change of the protein at this temperature. A model for the description of heat inactivation in the two temperature ranges is proposed.

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Kinetic of oxidation of methyl orange by vanadium(V) under conditions VO2+ and decavanadates coexist: Catalysis by Triton X-100 micellar medium

10.31221/osf.io/m9g7p ◽

2019 ◽

Author(s):

Chem Int

Keyword(s):

Methyl Orange ◽

Solution Ph ◽

Vanadium Concentration ◽

Limiting Behavior ◽

First Order ◽

First Order Kinetics ◽

Ph Range ◽

Kinetic Pattern ◽

Triton X ◽

Kinetics Of

The kinetics of oxidation of methyl orange by vanadium(V) {V(V)} has been investigated in the pH range 2.3-3.79. In this pH range V(V) exists both in the form of decavanadates and VO2+. The kinetic results are distinctly different from the results obtained for the same reaction in highly acidic solution (pH < 1) where V(V) exists only in the form of VO2+. The reaction obeys first order kinetics with respect to methyl orange but the rate has very little dependence on total vanadium concentration. The reaction is accelerated by H+ ion but the dependence of rate on [H+] is less than that corresponding to first order dependence. The equilibrium between decavanadates and VO2+ explains the different kinetic pattern observed in this pH range. The reaction is markedly accelerated by Triton X-100 micelles. The rate-[surfactant] profile shows a limiting behavior indicative of a unimolecular pathway in the micellar pseudophase.

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Purification and properties of a stable β-glucosidase from an extremely thermophilic anaerobic bacterium

Biochemical Journal ◽

10.1042/bj2430779 ◽

1987 ◽

Vol 243 (3) ◽

pp. 779-787 ◽

Cited By ~ 42

Author(s):

M L Patchett ◽

R M Daniel ◽

H W Morgan

Keyword(s):

Anaerobic Bacterium ◽

Thermal Inactivation ◽

First Order ◽

First Order Kinetics ◽

Purification And Properties ◽

Wide Range ◽

Optimum Ph ◽

Exclusion Chromatography ◽

Beta Glucosidase ◽

Beta Galactosidase

A beta-glucosidase (EC 3.2.1.21) was purified to homogeneity from cell-free extracts of an extremely thermophilic anaerobic bacterium. The enzyme has an Mr of 43,000 as determined by molecular-exclusion chromatography, has a pI of 4.55 and shows optimum activity at pH 6.2. The enzyme is active against a wide range of aryl beta-glycosides and beta-linked disaccharides, with beta-galactosidase activity only slightly less than beta-glucosidase activity, and significant beta-xylosidase activity. Lineweaver-Burk plots for p-nitrophenyl beta-glucoside, o-nitrophenyl beta-glucoside and cellobiose substrates are biphasic concave-downwards. Inhibition of the beta-glucosidase by substrates and glucose is negligible. Thermal inactivation follows first-order kinetics, with t1/2 (65 degrees C) 45 h, t1/2 (75 degrees C) 47 min and t1/2 (85 degrees C) 1.4 min and a deactivation energy of 380 kJ/mol at pH 6.2. At pH 7.0, which is the optimum pH for thermostability, t1/2 (75 degrees C) is 130 min. At 75 degrees C, at pH 6.2, the thermostability is enhanced about 8-fold by 10% (w/v) glycerol, about 6-fold by 0.2 M-cellobiose and about 3-fold by 5 mM-dithiothreitol and 5 mM-2-mercaptoethanol.

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Effect of temperature and/or pressure on lactoperoxidase activity in bovine milk and acid whey

Journal of Dairy Research ◽

10.1017/s0022029901005118 ◽

2001 ◽

Vol 68 (4) ◽

pp. 625-637 ◽

Cited By ~ 27

Author(s):

LINDA R. LUDIKHUYZE ◽

WENDIE L. CLAEYS ◽

MARC E. HENDRICKX

Keyword(s):

High Temperature ◽

Atmospheric Pressure ◽

Thermal Inactivation ◽

Bovine Milk ◽

Antagonistic Effect ◽

Effect Of Temperature ◽

Pressure Treatment ◽

First Order ◽

First Order Kinetics ◽

High Temperature Sensitivity

At atmospheric pressure, inactivation of lactoperoxidase (LPO) in milk and whey was studied in a temperature range of 69–73 °C and followed first order kinetics. Temperature dependence of the first order inactivation rate constants could be accurately described by the Arrhenius equation, with an activation energy of 635·3±70·7 kJ/mol for raw bovine milk and 736·9±40·9 kJ/mol for diluted whey, indicating a very high temperature sensitivity. On the other hand, LPO is very pressure resistant and not or only slightly affected by treatment at pressure up to 700 MPa combined with temperatures between 20 and 65 °C. Both for thermal and pressure treatment, stability of LPO was higher in milk than in diluted whey. Besides, a very pronounced antagonistic effect between high temperature and pressure was observed, i.e. at 73 °C, a temperature where thermal inactivation at atmospheric pressure occurs rapidly, application of pressure up to 700 MPa exerted a protective effect. At atmospheric pressure, LPO in diluted whey was optimally active at a temperature of about 50 °C. At all temperatures studied (20–60 °C), LPO remained active during pressure treatment up to 300 MPa, although the activity was significantly reduced at pressures higher than 100 MPa. The optimal temperature was found to shift to lower values (30–40 °C) with increasing pressure.

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Purification and properties of an aryl β-xylosidase from a cellulolytic extreme thermophile expressed in Escherichia coli

Biochemical Journal ◽

10.1042/bj2730645 ◽

1991 ◽

Vol 273 (3) ◽

pp. 645-650 ◽

Cited By ~ 17

Author(s):

R C Hudson ◽

L R Schofield ◽

T Coolbear ◽

R M Daniel ◽

H W Morgan

Keyword(s):

Escherichia Coli ◽

Thermal Inactivation ◽

Competitive Inhibitor ◽

Coli Strain ◽

Extreme Thermophile ◽

First Order ◽

Optimal Activity ◽

First Order Kinetics ◽

Purification And Properties ◽

Optimum Ph

An aryl beta-xylosidase was purified to homogeneity from an Escherichia coli strain containing a recombinant plasmid carrying a beta-xylosidase (EC 3.2.1.37) gene from the extremely thermophilic anaerobic bacterium isolate Tp8T6.3.3.1 (‘Caldocellum saccharolyticum’). It has a pI of 4.3 and shows optimal activity at pH 5.7. The enzyme is highly specific, acting on o- and p-nitrophenyl beta-D-xylopyranosides and minimally on p-nitrophenyl alpha-L-arabinopyranoside. It does not act on xylobiose. The Km for p-nitrophenyl beta-D-xylopyranoside at the optimum pH for activity is 10 mM, and at pH 7.0 is 6.7 mM. Xylose is a competitive inhibitor with Ki 40 mM. Thermal inactivation follows first-order kinetics at 65 and 70 degrees C with t1/2 values of 4.85 h and 40 min respectively. The t1/2 at 70 degrees C is increased 3-fold and 4-fold by the addition of 0.5 mg of BSA/ml and 2 mM-dithiothreitol respectively.

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Effect of liposomal phospholipid composition on cholesterol transfer between microsomal and liposomal vesicles

Biochemical Journal ◽

10.1042/bj2380647 ◽

1986 ◽

Vol 238 (3) ◽

pp. 647-652 ◽

Cited By ~ 20

Author(s):

C Bhuvaneswaran ◽

K A Mitropoulos

Keyword(s):

Activation Energy ◽

Enzyme Activity ◽

Control System ◽

Phospholipid Composition ◽

Acyltransferase Activity ◽

Phosphatidylcholine Liposomes ◽

First Order ◽

First Order Kinetics ◽

Phospholipid Liposomes

Preincubation of rat liver microsomal vesicles at 37 degrees C in the presence of [3H]cholesterol/phospholipid liposomes results in a net transfer of cholesterol from liposomes to microsomal vesicles. This transfer follows first-order kinetics. For similar concentrations of the donor vesicles, rates of transfer are about 6-8 times lower with cholesterol/sphingomyelin liposomes compared with cholesterol/phosphatidylcholine liposomes. Also, transfer of cholesterol from cholesterol/sphingomyelin liposomes to microsomal vesicles reveals a larger activation energy than for the process from cholesterol/phosphatidylcholine liposomes. There is a significant correlation between the amount of liposomal cholesterol transferred to microsomal vesicles during preincubation and the increase found with acyl-CoA:cholesterol acyltransferase activity in these microsomes over their corresponding controls. If, however, liposomes made solely of phospholipids are substituted for the cholesterol/phospholipid liposomes in the preincubation system containing microsomal vesicles, then the acyl-CoA:cholesterol acyltransferase activity is decreased compared with the corresponding control system. Both sphingomyelin and phosphatidylcholine liposomes are equally effective in decreasing the enzyme activity. These results offer direct kinetic evidence for the positive correlation between cholesterol and sphingomyelin found in vivo in biological membranes.

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Optimization, Kinetics, Thermodynamic and Arrhenius Model of the Removal of Ciprofloxacin by Internal Electrolysis with Fe-Cu and Fe-C Materials

Processes ◽

10.3390/pr9122110 ◽

2021 ◽

Vol 9 (12) ◽

pp. 2110

Author(s):

Tra Huong Do ◽

Xuan Linh Ha ◽

Thi Tu Anh Duong ◽

Phuong Chi Nguyen ◽

Ngoc Bich Hoang ◽

...

Keyword(s):

Activation Energy ◽

Ph Value ◽

Arrhenius Model ◽

First Order ◽

Chemical Plating ◽

First Order Kinetics ◽

Internal Electrolysis ◽

Plating Method ◽

Rapid Removal ◽

Pseudo First Order

The ciprofloxacin (CIP) removal ability of a Fe-Cu electrolytic material was examined with respect to pH (2–9), time (15–150 min), shaking speed (100–250 rpm), material mass (0.2–3 g/L), temperature (298, 308, 323) and initial CIP concentration (30–200 mg/L). The Fe-Cu electrolytic materials were fabricated by the chemical plating method, and Fe-C materials were mechanically mixed from iron powder and graphite. The results show that at a pH value of 3, shaking time 120 min, shaking speed 250 rpm, a mass of Fe-Cu, Fe-C material of 2 g/L and initial CIP concentration of 203.79 mg/L, the CIP removal efficiency of Fe-Cu material reached 90.25% and that of Fe-C material was 85.12%. The removal of CIP on Fe-Cu and Fe-C materials follows pseudo-first-order kinetics. The activation energy of CIP removal of Fe-Cu material is 14.93 KJ/mol and of Fe-C material is 16.87 KJ/mol. The positive ΔH proves that CIP removal is endothermic. A negative entropy of 0.239 kJ/mol and 0.235 kJ/mol (which is near zero and is also relatively positive) indicated the rapid removal of the CIP molecules into the removed products.

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Reactions with half-lives of several years

Australian Journal of Chemistry ◽

10.1071/ch9640406 ◽

1964 ◽

Vol 17 (4) ◽

pp. 406 ◽

Cited By ~ 8

Author(s):

GA Bottomley ◽

GL Nyberg

Keyword(s):

Activation Energy ◽

Thermal Decomposition ◽

Gas Phase ◽

Virial Coefficient ◽

Energy Equation ◽

Second Virial Coefficient ◽

First Order ◽

First Order Kinetics ◽

Reciprocal Temperature ◽

Temperature Activation

The gas-phase thermal decomposition of dimethyldiazirine, (CH3)2CN2, at very slow rates has been investigated using precision gas-volumetric techniques previously applied to second virial coefficient studies. At 50-70� the first-order kinetics correspond to half-lives about 0.3-3.0 years. The present results, together with data obtained by other workers using conventional apparatus at 124-174�, fit a single log rate-reciprocal temperature activation energy equation.

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