Thermal inactivation parameters for alkaline proteinases from north sea cod (<i>Gadus morhua</i>) and bovine α‐chymotrypsin

Amin, Amiza Mat; Owusu‐Apenten, Richard

doi:10.1002/jsfa.2740660317

Cited by 18 publications

(7 citation statements)

References 4 publications

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“…Thermal unfolding of cod PMS-trypsin began at 40°C compared with 50°C for bovine PMStrypsin. Such results are in agreement with the finding that heating to about 40°C leads to irreversible thermal unfolding of Atlantic cod trypsin (Simpson et al 1990; Amiza and Owusu Apenten 1994). The T, value for cod PMS-trypsin was 46( k 1.4)"C ( Table 2) The stability curves for cod and bovine PMS-trypsins are given (Fig 7) as a graph of experimental and theoretical AG values (calculated according to eqn (5), continuous line) plotted against temperature.…”

Section: Thermal Unfolding Of Cod and Bovine Pms-trypsinssupporting

confidence: 92%

“…The isolation, characterisation and possible applications of cod digestive proteinases have been extensively studied (Asgeirsson et a1 1989;Raae and Walther 1989;Simpson et al 1989Simpson et al , 1990Haard 1992;Bjarnason and Asgeirsson 1993). For the time being, only a few reports concerning the irreversible inactivation of fish proteinases have been published (Bjarnason and Asgeirsson 1993;Amiza and Owusu Apenten 1994). At the time of writing, there have been no previous reports concerning urea and/or heat unfolding of trypsin from marine sources.…”

Section: Introductionmentioning

confidence: 99%

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Urea and Heat Unfolding of Cold-Adapted Atlantic Cod(Gadusmorhua) Trypsin and Bovine Trypsin

Amin

Owusu‐Apenten

1996

J. Sci. Food Agric.

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The reversible unfolding reactions for phenylmethylsulphonyl fluoride (PMSF)‐modified trypins from Atlantic cod (cod PMS‐trypsin) and cattle (bovine PMS‐trypsin) were monitored by fluorescence spectrophotometry as a function of urea concentration and temperature. For urea unfolding at 25°C, the free energy change at zero concentration of urea (ΔG(H2O)) for cod PMS‐trypsin was 11(±4·4) kJ mol−1 compared with 18(±1·14) kJ mol−1 for bovine PMS‐trypsin, while the mid‐point concentration for urea unfolding curve ([urea]1/2) was 3·0(±0·57) M and 4·1(±0·16) M, respectively. From studies of enzyme heat unfolding, the mid point temperature of the thermal unfolding curve (Tm) was 46(±1·4)°C for cod PMS‐trypsin compared with 57(±2)°C for bovine PMS‐trypsin. The standard free energy change (ΔG°) for reversible thermal unfolding of cod PMS‐trypsin was 9(±1) kJ mol−1 compared with 19(±1) kJ mol−1 for bovine PMS‐trypsin. Values for the enthalpy (ΔHm), entropy (ΔSm) and heat capacity (ΔCp) for heat unfolding are compared. Results from urea and thermal unfolding studies show that cod PMS‐trypsin has a significantly lower conformational stability than bovine PMS‐trypsin.

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Section: Thermal Unfolding Of Cod and Bovine Pms-trypsinssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Urea and Heat Unfolding of Cold-Adapted Atlantic Cod(Gadusmorhua) Trypsin and Bovine Trypsin

Amin

Owusu‐Apenten

1996

J. Sci. Food Agric.

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“…When the temperature reaches 40 8C, the majority of the intestinal proteolytic enzymes from cod becomes thermally denatured [55][56][57]; however, some enzymes in the liver fraction thrive at temperatures up to 60 8C [58]. It is therefore likely that the proteolytic activity at 55 8C is largely attributable to the externally added enzyme, but some contribution from endogenous enzymes cannot be excluded.…”

Section: Discussionmentioning

confidence: 96%

Enzymatic hydrolysis of Atlantic cod (Gadus morhua L.) viscera

Aspmo¹,

Horn²,

Eijsink³

2005

Process Biochemistry

176

116

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“…The data obtained from the thermal stability profile were used to analyze some thermodynamic parameters related to the grape PPO activity. Thermal inactivation rate constants were calculated by comparing the activity changes upon heat treatment with the unheated enzyme extracts as reported by Amiza and Apenten (1994). The activation energy for the denaturation of the enzyme was determined by an Arrhenius plot of log reaction rate constants (ln k ) versus the reciprocal of the absolute temperature.…”

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confidence: 99%

Izmir Grape Polyphenol Oxidase (Vitis Vinifera L.): Partial Purification and Some Kinetic Properties

Önez

Karakuş

Pekyardımcı³

2008

J Food Biochemistry

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Polyphenol oxidase (PPO) was extracted from the Izmir grape fruit (Vitis vinifera L.) and its characteristics were studied. The PPO enzyme was purified 2.2‐fold by (NH4)2SO4 precipitation and 26.1‐fold by gel filtration chromatography. This partially purified enzyme obtained from dialysis migrated as one band with catechol substrate, four bands with Coomassie brilliant R‐250 (NATIVE‐PAGE) native system and as six bands of 34, 30, 22, 18, 16 and 15 kDa on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE). The sample obtained from dialysis after ammonium sulfate precipitation was used for the characterization of partially purified enzyme. Substrate specificity experiments were carried out with catechol, 4‐methyl catechol, l‐tyrosine, pyrogallol, p‐cresol, gallic acid and caffeic acid. Michael–Menten constant and maximum velocity values were 3.65 mM and 1,971.6 ΔA/dak, respectively, with catechol substrate. Optimum pH for the PPO enzyme were determined at 7.2, 7.0, 7.4, 7.2, 6,4, 6.7 and 5.7 using catechol, 4‐methyl catechol, l‐tyrosine, pyrogallol, p‐cresol, gallic acid and caffeic acid substrates, respectively. Optimum temperature for maximum PPO activity was 25C for catechol. Heat inactivation studies showed a significiant decrease in enzymatic activity at temperatures above 45C. Activation energy was calculated to be 12.4 kcal/mol. The most potent inhibitors for the grape PPO were thiourea, sodium diethyldithiocarbamate and sodium azide. Inhibition constants were calculated for L‐ascorbic acid, l‐cysteine and β‐mercaptoethanol at the optimum pH of PPO activity. PRACTICAL APPLICATIONS The polyphenol oxidase enzymes isolated from different species have been used to control the pollution in water, to remove and transform toxic compounds of industrial processes and to determine catechol and other biologically active catecholamines in biologic liquids as an enzymatic biosensor.

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Thermal inactivation parameters for alkaline proteinases from north sea cod (Gadus morhua) and bovine α‐chymotrypsin

Cited by 18 publications

References 4 publications

Urea and Heat Unfolding of Cold-Adapted Atlantic Cod(Gadusmorhua) Trypsin and Bovine Trypsin

Urea and Heat Unfolding of Cold-Adapted Atlantic Cod(Gadusmorhua) Trypsin and Bovine Trypsin

Enzymatic hydrolysis of Atlantic cod (Gadus morhua L.) viscera

Izmir Grape Polyphenol Oxidase (Vitis Vinifera L.): Partial Purification and Some Kinetic Properties

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