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Wyszukujesz frazę "inactivation kinetics" wg kryterium: Wszystkie pola


Wyświetlanie 1-5 z 5
Tytuł:
Laccase activity and stability in the presence of menthol-based ionic liquids
Autorzy:
Feder-Kubis, Joanna
Bryjak, Jolanta
Powiązania:
https://bibliotekanauki.pl/articles/1039478.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
laccase
ionic liquid
two-liquid-phase system
enzyme stability
inactivation kinetics
Opis:
Laccases attract attention due to their potential for manufacturing pharmaceutical intermediates from a wide array of phenolic and non-phenolic substrates that are sparingly soluble in water. Because of the high polarity of ionic liquids (ILs), they can dissolve polar and nonpolar compounds and are claimed as "green" alternative for volatile organic solvents. The main aim of this work was to find water-immiscible ILs suitable for Cerrena unicolor laccase. For that five ILs with bis(trifluoromethanesulfonyl)imide anions coupled with cations derived from natural alcohol - (1R,2S,5R)-(-)-menthol were synthesized, namely: (I) 3-butyl-1-[(1R,2S,5R)-(-)-menthoxymethyl]imidazolium, (II) 1-[(1R,2S,5R)-(-)-menthoxymethyl]-3-heptylimidazolium, (III) 1-[(1R,2S,5R)-(-)-menthoxymethyl]-3-methylpyridinium, (IV) heptyl[(1R,2S,5R)-(-)-menthoxymethyl]dimethylammonium, and (V) decyl[(1R,2S,5R)-(-)-menthoxymethyl]dimethylammonium ions. Laccase activity was tested in buffer saturated with ILs whereas stability tests in biphasic systems lasted 5 days. It was shown that ILs I, III-V did not significantly alter laccase activity (being 90-123% respective to the buffer) whereas IL II decreased reactivity in 20%. Stability tests revealed that ILs I, IV and V increased enzyme stability even more than in the buffer. For mathematical formalization of inactivation courses, isoenzyme model was applied but this model fitted experimental data only for sets obtained in the buffer (control) and in the presence of IL II. In the other cases, first-order reaction model was sufficient. This shows that ILs, even at very low concentrations, influence conformational stability of proteins, which is dependent on the cation structure. In general, the imidazolium (I) and ammonium (IV) salts with shorter alkyl chains supported laccase activity and stability.
Źródło:
Acta Biochimica Polonica; 2013, 60, 4; 741-745
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kinetics of inactivation of glutamate decarboxylase by cysteine-specific reagents.
Autorzy:
McCormick, Sara
Tunnicliff, Godfrey
Powiązania:
https://bibliotekanauki.pl/articles/1044156.pdf
Data publikacji:
2001
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
mercuric chloride
Escherichia coli
DTNB
cysteinyl residues
p-chloromercuribenzoate
glutamate decarboxylase
inactivation
sulfhydryl groups
Opis:
Mercuric chloride, p-chloromercuribenzoate and 5,5'-dithiobis(2-nitrobenzoic acid) irreversibly inhibited the activity of Escherichia coli glutamate decarboxylase. Their second order rate constants for inactivation are 0.463 μM-1min-1, 0.034 μM-1min-1, 0.018 μM-1min-1, respectively. The characteristics of the inhibition by the three thiol-group reagents supports the idea that cysteinyl residues at the binding sites for the cofactor and/or the substrate are important for enzyme activity in E. coli.
Źródło:
Acta Biochimica Polonica; 2001, 48, 2; 573-578
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kinetyka inaktywacji lakazy w obecności rozpuszczalników organicznych mieszających się z wodą
Kinetics of laccase inactivation in the presence of water miscible organic solvents
Autorzy:
Bryjak, J.
Białowąs, K.
Kucewicz, A.
Powiązania:
https://bibliotekanauki.pl/articles/2071700.pdf
Data publikacji:
2012
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
lakaza
rozpuszczalniki mieszające się z wodą
inaktywacja
modelowanie matematyczne
laccase
water-miscible solvents
inactivation
mathematical modeling
Opis:
W badaniach nad inaktywacją lakazy w mieszających się z wodą rozpuszczalnikach organicznych wykorzystano etanol, dimetylofomamid, acetonitryl i 2-propanol w stężeniach 0-60% (obj/obj). Na podstawie spadku aktywności enzymu dobrano model seryjny, jako pozwalający odwzorować proces we wszystkich badanych przypadkach. Stwierdzono, że utrata aktywności enzymu w rozpuszczalnikach w stężeniach poniżej 30% jest spowodowana częściowym rozfałdowaniem białka w kontakcie z tymi związkami.
In the search on laccase inactivation in water miscible organic solvents, acetonitrile, dimethyl formamide, ethanol and 2-propanol were used in centrations from 0% to 60% (vol/vol). On the base of activity decrease in time, the kinetic model based on series mechanism was selected as the best for proper mapping of all experimental data. It was stated that the laccase inactivation below 30% of solvents concentration was caused by partial defolding of the enzyme molecules.
Źródło:
Inżynieria i Aparatura Chemiczna; 2012, 4; 98-100
0368-0827
Pojawia się w:
Inżynieria i Aparatura Chemiczna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kinetics properties of polyphenol oxidase in hawthorn (Crataegus spp.)
Autorzy:
Saeidian, S.
Powiązania:
https://bibliotekanauki.pl/articles/10795.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
kinetic property
polyphenol oxidase
hawthorn
Crataegus
purification
inhibition
thermal inactivation
Opis:
Polyphenol oxidase (PPO) from hawthorn was extracted and partially purified through (NH4)2SO4 precipitation, dialysis and ion exchange chromatography. The activity of polyphenol oxidase was investigated in Crataegus spp. Spectrophotometric method was used to assay the enzyme activity and the kinetic constants - maximum enzyme velocity (Vmax) and Michealis - Menten constant (Km). Of the substrates tested, catechol was the best substrate for PPO with a Km value of 2.2 mM. The optimum pH for PPO activity was found to be 7. The enzyme showed high activity over a broad pH range of 4 - 8. The optimal pH and temperature for enzyme activity were found to be 7 and 40-45 °C, respectively. km value for hawthorn PPO is calculated 22 mM for catechol and 6.7 mM for pyrogallol and 9.7 mM for L-dopa. As can be seen, affinity of PPOs for various substrates varies widely. The enzyme showed a broad activity over a broad pH and temperature range. The thermal inactivation studies showed that the enzyme is heat resistant. The enzyme showed the highest activity toward pyrogallol and no activity toward tyrosine. Of the inhibitors tested, the most potent inhibitors were kojic acid, cysteine and glycine , respectively.
Źródło:
International Letters of Natural Sciences; 2014, 20
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of Daftardar-Gejiji and Jafari method to kinetic analysis of thermal inactivation of Jack bean urease
Autorzy:
Sobamowo, G.
Adeleye, O.
Powiązania:
https://bibliotekanauki.pl/articles/973622.pdf
Data publikacji:
2018
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
kinetics
thermal activation
Jack bean urease
enzyme
biotechnology
Daftardar-Gejiji and Jafari method
Kinetyka
analiza kinetyczna
inaktywacja termiczna
enzym
ureaza
biotechnologia
metoda Daftardar-Gejiji i Jafari
Opis:
Jack bean urease has been used as a good catalyst for hydrolysis of urea in various applications such as biotechnology and biomedical engineering. The wide range of applications require proper understanding of the thermal inactivation of the enzyme. Consequently, the theoretical analysis of the enzyme kinetic of the thermal inactivation is required. In this paper, a new iterative method proposed by Daftardar-Gejiji and the Jafari method is applied to analyse the kinetic of thermal inactivation of jack bean urease (EC3.5.1.5). The kinetics of the urease consist of three-reaction steps and included the Arrhenius equation for temperature-dependent rate constants as well as the temperature change in the initial heating period. The approximate analytical solutions are verified with results of numerical method using Runge-Kutta with the shooting method, and good agreements are established between the results of the methods. From the analytical investigation, it is established that the molar concentration of the native enzyme decreases as the time increases while the molar concentration of the denatured enzyme increases as the time increases. The time taken to reach the maximum value of the molar concentration of the native enzyme is the same as the time taken to reach the minimum value of the molar concentration of the denature enzyme. It is hoped that the information given in this theoretical investigation will assist in the kinetic analysis of thermal inactivation of the experimental results over handling rate constants and molar concentrations.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2018, 17, 2; 65-76
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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