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

1987 ◽  
Vol 243 (3) ◽  
pp. 779-787 ◽  
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.

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

1991 ◽  
Vol 273 (3) ◽  
pp. 645-650 ◽  
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.

Purification and properties of 6-phosphogluconate dehydrogenase from Penicillium duponti and Penicillium notatum

1972 ◽  
Vol 18 (8) ◽  
pp. 1289-1298 ◽  
Author(s):  
Hugh M. Miller ◽  
Maxwell G. Shepherd
Keyword(s):  
Protein Concentration ◽  
Thermal Inactivation ◽  
Sodium Dodecylsulfate ◽  
Thermophilic Enzyme ◽  
Penicillium Notatum ◽  
First Order ◽  
Phosphogluconate Dehydrogenase ◽  
First Order Kinetics ◽  
High Protein Concentration ◽  
Purification And Properties

6-Phosphogluconate dehydrogenase was isolated and partially purified from the thermophilic fungus Penicillium duponti and the mesophilic fungus Penicillium notatum. The specific activities of the purified enzymes were 17.5 and 22.0 respectively. Optimal activity was obtained at pH 8.0 for both enzymes. Non-linear Arrhenius plots were found for both enzymes with breaks at 30 °C for P. duponti 6-phosphogluconate dehydrogenase and 19 °C for P. notatum 6-phosphogluconate dehydrogenase. The thermal inactivation of 6-phosphogluconate dehydrogenase from both fungi exhibited first order kinetics, and the rate of inactivation for the thermophilic enzyme between 25 °C and 45 °C was only 25% that of the mesophilic enzyme. 6-Phosphogluconate dehydrogenase from both sources was protected from thermal inactivation by 6-phosphogluconic acid, high salt concentration, and high protein concentration. The thermophilic enzyme was found to be more resistant to the denaturants urea, acetamide, and sodium dodecylsulfate.

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

2001 ◽  
Vol 68 (4) ◽  
pp. 625-637 ◽  
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.

scholarly journals Modeling the Effect of Plants and Peat on Evapotranspiration in Constructed Wetlands

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Florent Chazarenc ◽  
Simon Naylor ◽  
Yves Comeau ◽  
Gérard Merlin ◽  
Jacques Brisson
Keyword(s):  
Phragmites Australis ◽  
Constructed Wetlands ◽  
Typha Latifolia ◽  
Growth Conditions ◽  
First Order ◽  
First Order Kinetics ◽  
Hydraulic Behaviour ◽  
Degradation Rates ◽  
Wide Range ◽  
Main Effect

Evapotranspiration (ET) in constructed wetlands (CWs) represents a major factor affecting hydrodynamics and treatment performances. The presence of high ET was shown to improve global treatment performances, however ET is affected by a wide range of parameters including plant development and CWs age. Our study aimed at modelling the effect of plants and peat on ET in CWs; since we hypothesized peat could behave like the presence of accumulated organic matter in old CWs. Treatment performances, hydraulic behaviour, and ET rates were measured in eight 1 m2CWs mesocosm (1 unplanted, 1 unplanted with peat, 2 planted withPhragmites australis, 2 planted withTypha latifoliaand 2 planted withPhragmites australiswith peat). Two models were built using first order kinetics to simulate COD and TKN removal with ET as an input. The effect of peat was positive on ET and was related to the better growth conditions it offered to macrophytes. Removal efficiency in pilot units with larger ET was higher for TKN. On average, results show for COD ak20value of 0.88d-1and 0.36d-1for TKN. We hypothesized that the main effect of ET was to concentrate effluent, thus enhancing degradation rates.

scholarly journals Thermostability and thermodynamic characterization of sprouted pearl millet ?-amylases for its biotechnological applications

2017 ◽  
Vol 52 (3) ◽  
pp. 159-166 ◽  
Author(s):  
KU Agbo ◽  
PC Okwuenu ◽  
AL Ezugwu ◽  
SOO Eze ◽  
FC Chilaka
Keyword(s):  
Pearl Millet ◽  
Thermal Inactivation ◽  
Arrhenius Plot ◽  
Thermodynamic Characterization ◽  
First Order ◽  
First Order Kinetics ◽  
Glucose Syrup ◽  
Increasing Demand ◽  
Thermostable Amylase

There is an increasing demand for amylolytic products such as glucose syrup in biotechnological industries. Starch liquification by ?-amylase must take place at temperatures higher than the gelatinization temperatures and the use for thermostable ?-amylase is therefore required. Two (or) isotypes namely amy-1 and amy-2 of ?-amylase from pearl millet have been investigated for their thermostability and thermodynamic characterization. Thermal inactivation of ?-amylase follows first order kinetics which varies with time and product during inactivation process. The half-life of ?-1 was 198 mins at 50°C. The Ea (inact) was calculated using Arrhenius plot gave 22.00 KCalmol-1K-1 for ?-1 and 19.44 KCalmol-1K-1 for ?-2. The Z-values were 22.52°C and 25.38°C for ?-1 and ?-2, respectively. The thermodynamic parameters: the enthalpy change of inactivation ?H (inact)  had 87.815 KJmol-1K-1 at 50°C for ?-1 and 78.56 KJmol-1K-1 at 50°C for ?-2. The change in free energy of inactivation ?G (inact) of ?-1 and ?-2 were 105.5 KJmol-1K-1 and 104.33 KJmol-1K-1 at 50°C, respectively. The entropy of inactivation ?S (inact) values for ?-1 and ?-2 are calculated as -54.80 JMol-1K-1 and -79 JMol-1K-1 at 50°C. This suggest that the ?-1 and ?-2 are thermostable.Bangladesh J. Sci. Ind. Res. 52(3), 159-166, 2017

scholarly journals ENZYMATIC BREAKDOWN OF THREONINE BY THREONINE ALDOLASE

1954 ◽  
Vol 38 (2) ◽  
pp. 181-196 ◽  
Author(s):  
Shih-Chia C. Lin ◽  
David M. Greenberg
Keyword(s):  
Pyridoxal Phosphate ◽  
Thermal Inactivation ◽  
Enzyme Reaction ◽  
Enzyme Concentration ◽  
Ph Optimum ◽  
First Order ◽  
Threonine Aldolase ◽  
First Order Kinetics ◽  
Michaelis Constants ◽  
Tris Maleate

1. The enzyme which splits threonine to acetaldehyde and glycine has been partially purified from rat liver (five- to sixfold purification) and the name threonine aldolase proposed for it. 2. The general properties of threonine aldolase have been studied. The enzyme is unstable to a pH below 5. The pH optimum of the enzyme reaction is at 7.5–7.7. The initial rate of production of acetaldehyde is proportional to the enzyme concentration, and when the enzyme concentration is constant, the production of acetaldehyde is proportional to the time, provided that the substrate is in excess. The enzyme is inhibited by the carbonyl group reagent, hydroxylamine. Attempts to demonstrate that pyridoxal phosphate is a cofactor were unsuccessful. 3. The enzyme splits only L-allothreonine and L-threonine and is inactive against the D-forms of these amino acids. 4. The enzyme reaction on DL-allothreonine follows first order kinetics. From the first order velocity constants and the initial rates of the rates of the reaction at various substrate concentrations the Michaelis constant, Ks, for this substrate has been evaluated. Michaelis constants have also been determined for threonine. 5. The optimum temperature for the enzymatic breakdown of DL-allothreonine at pH 7.65 was found to be 50°C. in phosphate buffer and 48°C. in tris-maleate buffer. The rate of thermal inactivation of the enzyme threonine aldolase obeys a first order reaction. The heat of thermal inactivation was calculated by the aid of the van't Hoff-Arrhenius equation to be 43,000 cal. per mole for the temperature range 41.2–46.6°C. 6. Equivalent amounts of acetaldehyde and glycine were formed from DL-allothreonine and the enzymatic breakdown of DL-allothreonine was found to be irreversible.

scholarly journals Kinetics And Thermodynamic Properties of Trametes Polyzona WRF03 Laccase

2021 ◽  
Author(s):  
Tobechukwu Christian Ezike ◽  
Arinze Linus Ezugwu ◽  
Jerry Okwudili Udeh ◽  
Kenneth Chinekwu Ugwuoke ◽  
Sabinus Oscar Onyebuchi Eze ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Denaturation ◽  
Thermal Inactivation ◽  
Heat Inactivation ◽  
First Order ◽  
First Order Kinetics ◽  
Temperature Ranges ◽  
Z Value ◽  
Gibb’S Free Energy ◽  
Ph Range

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.

High-Temperature Short-Time Inactivation of Peroxidase by Direct Heating with a Five-Channel Computer-Controlled Thermoresistometer†

1997 ◽  
Vol 60 (8) ◽  
pp. 967-972 ◽  
Author(s):  
CARMEN RODRIGO ◽  
ANDRÉS ALVARRUIZ ◽  
ANTONIO MARTÍNEZ ◽  
ANA FRÍGOLA ◽  
MIGUEL RODRIGO
Keyword(s):  
High Temperature ◽  
Horseradish Peroxidase ◽  
Thermal Inactivation ◽  
Inactivation Kinetics ◽  
First Order ◽  
First Order Kinetics ◽  
High Temperature Short Time ◽  
Computer Controlled ◽  
Short Time ◽  
Kinetics Of

The thermal inactivation kinetics of horseradish and asparagus peroxidase in high-temperature short-time conditions was studied by heating in a five-channel computer-controlled thermoresistometer. Horseradish peroxidase was heated between 111.5 and 145°C and the reaction was analyzed assuming that two isoenzymes with EaL = 44.1 and Eas = 22.0 kcal/mol were present. Asparagus peroxidase heated from 110 to l20°C reacted with first-order kinetics, with Ea = 20 kcal/mol. The five-channel computer-controlled thermoresistometer enabled us to study the inactivation kinetics of the more labile fraction of horseradish peroxidase at temperatures above 100°C; this equipment was suitable for studying the heat resistance of peroxidase at high temperatures.

Solvent Effects on the Racemization of Optically Active Tris(N-substituted carbamodithioato)cobalt (III) Complexes

1979 ◽  
Vol 32 (8) ◽  
pp. 1653 ◽  
Author(s):  
LR Gahan ◽  
MJ O'Conner
Keyword(s):  
Carbon Tetrachloride ◽  
Solvent Effects ◽  
Reaction Mechanisms ◽  
Activation Parameters ◽  
Optically Active ◽  
Isokinetic Relationship ◽  
First Order ◽  
First Order Kinetics ◽  
Thermodynamic Activation Parameters ◽  
Wide Range

The thermal racemization in solution of some optically active tris(N-substituted carbamodithioato)- cobalt(III) complexes [N-substituents = diphenyl, dimethyl, diisopropyl, and tetramethylene (pyrrolidinyl)] has been measured polarimetrically in a range of solvents including dimethylformamide, acetonitrile, carbon tetrachloride, chlorobenzene, chloroform, toluene and ethanol. The metal-centred (Δ ↔ Λ) inversion reactions show first-order kinetics as expected for an intra- molecular process. Thermodynamic activation parameters for the reaction show that values of ΔS‡ occur over a wide range (from -124 to +60 J K-1 mol-1) as do the values of ΔH‡ (from 67�4 to 129�3 kJ mol-1). Values for ΔG‡ are reasonably constant. Although a similar mechanism for the metal-centred inversion is suggested for all compounds in the various solvents because of an observed isokinetic relationship between ΔH‡ and ΔS‡, with isokinetic temperatures in the range 312-369 K, it is clear that postulates of reaction mechanisms based on the value of ΔS‡ determined in only one solvent should be treated with caution. The optically active (-)546-tris(N,N-diisopropylcarbamodithioato)cobalt(III) complex photoracemizes in solution without decomposition. The rate of photoracemization is solvent-dependent being in the order bromoform � carbon tetrachloride ≈ chloroform �benzene.

Thermal Inactivation of Salmonella in Peanut Butter

2009 ◽  
Vol 72 (8) ◽  
pp. 1596-1601 ◽  
Author(s):  
LI MA ◽  
GUODONG ZHANG ◽  
PETER GERNER-SMIDT ◽  
VIJAYA MANTRIPRAGADA ◽  
IFEOMA EZEOKE ◽  
...  
Keyword(s):  
Thermal Inactivation ◽  
Peanut Butter ◽  
Weibull Model ◽  
Thermal Treatments ◽  
Death Rates ◽  
First Order ◽  
Log Reduction ◽  
First Order Kinetics ◽  
Large Populations ◽  
Sporadic Cases

The objective of this study was to determine the rates of thermal inactivation of three Salmonella Tennessee strains in peanut butter associated with an outbreak and to compare them to the rates of inactivation of Salmonella strains of other serotypes (Enteritidis, Typhimurium, and Heidelberg) (SSOS) and of clinical isolates of Salmonella Tennessee from sporadic cases (STSC). Commercial peanut butter was inoculated with Salmonella isolates and heated at 71, 77, 83, and 90°C. The thermal inactivation curves were upwardly concave, indicating rapid death at the beginning (20 min) of heating followed by lower death rates thereafter. The first-order kinetics approach and nonlinear Weibull model were used to fit the inactivation curves and describe the rates of thermal inactivation of Salmonella in peanut butter. The calculated minimum times needed to obtain a 7-log reduction at 90°C for the composited three outbreak-associated strains were significantly greater (P < 0.05) than those of SSOS and STSC. Approximately 120 min were needed to reduce the outbreak strains of Salmonella Tennessee by 7 log, whereas 86 and 55 min were needed for SSOS and STSC, respectively. These results indicate that the outbreak-associated Salmonella strains were more thermotolerant than the other Salmonella strains tested, and this greater thermal resistance was not serotype specific. Thermal treatments of peanut butter at 90°C for less than 30 min are not sufficient to kill large populations (5 log CFU/g) of Salmonella in highly contaminated peanut butter.

Sign in / Sign up

Export Citation Format

Share Document