Wyniki wyszukiwania

1

Simplified solution of lactate dehydrogenase catalysed reaction

100%

Kuczek M.

Cellular and Molecular Biology Letters

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1998

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tom 03

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nr 2

The lactate dehydrogenase catalysed reaction shows lag phase. This lag phase is easy for explanation if the consecution of first and second order equilibrium reactions were assumed for calculation of pyruvate trace concentration. The same explanation was accepted for calculation of significant pyruvate concentration. For calculation significant pyruvate concentration the consecution of simple Michaelis - Menten type and second order reactions was assumed. The exact solution of reaction rate equations system for this complex reaction was counted.

2

Application of predictive microbiological tools for assuring the health safety of food

75%

Adamczewski K., Kowalik J.

Towaroznawcze Problemy Jakości. Polskie Towarzystwo Towaroznawcze

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2015

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nr 1

3

Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik

Bio-inspired trypsin-chitosan cross-linked enzyme aggregates: a versatile approach for stabilization through carrier-free immobilization

75%

Mageed H. A., Ezz N. A., Radwan R.

BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology

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2019

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tom 100

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nr 3

4

Pyrolysis kinetics of wood comparison of iso- and polythermal thermogravimetric methods

75%

Zakrzewski R.

Electronic Journal of Polish Agricultural Universities. Series Wood Technology

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2003

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tom 06

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nr 2

The values of kinetic parameters Ea (activation energy) and A (preexponential factor) were evaluated for different kinetic models using data from thermogravimetric (TGA) curves obtained in isothermal and polythermal conditions. It was found that diffuse kinetic models D3 and D4 aproximated the experimental data better than first order reaction model F1. The values of kinetic parameters for D3 and D4 models evaluated from both types of TG curves were comparable.

5

Evaluation of mixed-salt effects on thermodynamic and kinetic parameters of RNA polymerase - promoter DNA complexes in terms of equivalent salt concentrations. General applicability to DNA complexes

63%

Lozinski T., Wierzchowski K. L.

Acta Biochimica Polonica

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2009

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tom 56

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nr 4

695-702

Facile evaluation of mixed-salt effect on the strongly salt-dependent thermodynamic and kinetic parameters of protein-DNA complexes is of importance for relevant biochemical and biophysical studies. In pursuit of this aim, binding isotherms for open transcription complex (RPo) of Escherichia coli RNA polymerase (R) at λPR promoter DNA (P) were determined as a function of salt concentration in pure NaCl and Tris/HCl solutions, and as a function of [NaCl] in the presence of fixed concentrations of MgCl2 and Tris/HCl. A concept of equivalent salt concentrations, i.e. concentrations at which the binding equilibrium constant is the same, was introduced and applied for prediction of binding isotherms in mixed salt solutions. Full coincidence between the experimental and predicted isotherms indicated that individual contributions of salts to the global salt-effect are additive in a broad range of salt concentrations. A generalized formula for calculation of salt equivalents characteristic for any of the thermodynamic or kinetic parameters of a complex (e.g., free energy, binding equilibrium and association/dissociation kinetic rate constants) is presented and its applicability to a number of protein-DNA complexes and dsDNA melting demonstrated using authors' own and literature data.

6

Synthesis of instruments for cylindrical gear wheels rolling

63%

Kashura A., Kirichenko I., Vitrenko V.

Teka Komisji Motoryzacji i Energetyki Rolnictwa

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2010

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tom 10A

7

Inhibition and activation of enzymes. The effect of a modifier on the reaction rate and on kinetic parameters

63%

Fontes R., Ribeiro J. M., Sillero A.

Acta Biochimica Polonica

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2000

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tom 47

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nr 1

A combined analysis of enzyme inhibition and activation is presented, based on a rapid equilibrium model assumption in which one molecule of enzyme binds one molecule of substrate (S) and/or one molecule of a modifier X. The modifier acts as activator (essential or non-essential), as inhibitor (total or partial), or has no effect on the reaction rate (v), depending on the values of the equilibrium constants, the rate constants of the limiting velocity steps, and the concentration of substrate ([S]). Different possibilities have been analyzed from an equation written to emphasize that v=([X]) is, in general and at a fixed [S], a hyperbolic function. Formulas for Su (the value of [S], different from zero, at which v is unaffected by the modifier) and vsu (v at that particular [S]) were deduced. In Lineweaver-Burk plots, the straight lines related to different [X] generally cross in a point (P) with coordinates (Su, vsu). In certain cases, point P is located in the first quadrant which implies that X acts as activator, as inhibitor, or has no effect, depending on [S]. Furthermore, we discuss: (1) the apparent Vmax and Km displayed by the enzyme in different situations; (2) the degree of effect (inhibition or activation) observed at different concentrations of substrate and modifier; (3) the concept of Ke, a parameter that depends on the concentration of substrate and helps to evaluate the effect of the modifier: it equals the value of [X] at which the increase or decrease in the reaction rate is half of that achieved at saturating [X]. Equations were deduced for the general case and for particular situations, and used to obtain computer-drawn graphs that are presented and discussed. Formulas for apparent Vmax, Km and Ke have been written in a way making it evident that these parameters can be expressed as pondered means

8

Kinetic characterization of beta-fructofuranosidase isolated from the bird cherry leaves

63%

Ciepiela A. P., Sytykiewicz H., Czerniewicz P., Domanska D.

Biological Letters

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2005

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tom 42

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nr 2 Spec.Vol.

9

An analysis of thermal decomposition in oxidative conditions of model wood-based materials glued with amino resin

51%

Cichy W., Bartkowiak M.

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

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2012

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tom 77

An analysis of thermal decomposition in oxidative conditions of model wood-based materials glued with amino resin. The presented work includes the results of thermal analysis of model samples of particleboards glued with urea-formaldehyde resin with varying degree of sealing (5 ÷ 30%), which is a measurable factor changing the elemental nitrogen content in the samples. Changes of the kinetic parameters of the thermo-destruction reactions occurring in the air were observed as well.

10

Amino acid substitutions of His296 alter the catalytic properties of Zymomonas mobilis 10232 levansucrase

51%

Li S. Y., Chen M., Li G., Yan Y. L., Yu H. Y., Zhan Y. H., Peng Z. X., Wang J., Lin M.

Acta Biochimica Polonica

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2008

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tom 55

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nr 1

His296 of Zymomonas mobilis levansucrase (EC 2.4.1.10) is crucial for the catalysis of the transfructosylation reaction. The three-dimensional structures of levansucrases revealed the His296 is involved in the substrate recognition and binding. In this study, nine mutants were created by site-directed mutagenesis, in which His296 was substituted with amino acids of different polarity, charge and length. The substitutions of His296 with Arg or Trp retained partial hydrolysis and transfructosylation activities. The positively charged Lys substitution resulted in a 2.5-fold increase of sucrose hydrolysis. Substitutions with short (Cys or Ser), negatively charged (Glu) or polar (Tyr) amino acids virtually abolished both the activities. Analysis of transfructosylation products indicated that the mutants synthesized different oligosaccharides, suggesting that amino acid substitutions of His296 strongly affected both the enzyme activity and transfructosylation products.

11

Effects of early undernutrition on kinetic parameters of brain acetylcholinesterase from adult rats

51%

Rocha J. B. T., Emanuelli T., Pereira M. E.

Acta Neurobiologiae Experimentalis

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1993

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tom 53

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nr 3

12

Kinetic parameters of the degradative reactions of beta-carotene and capsanthin of hot red pepper stored in oxygen and vacuum atmosphere in presence or absence of light

51%

Morais H., Ramos C., Forgacs E., Cserhati T., Matos N., Almeida V., Oliveira J.

Herba Polonica

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2000

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tom 46

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nr 4

Celem badań było określenie wpływu przechowywania sproszkowanej czerwonej papryki w atmosferze tlenu i w warunkach próżniowych, zarówno na świetle, jak i bez światła, na rozkład dwóch barwników karotenoidowych: ß-karotenu i kapsantyny. Badania zawartości wymienionych składników karotenoidowych prowadzono za pomocą HPLC w warunkach odwróconych faz. Stwierdzono, że proces rozkładu obu barwników zachodził najszybciej w warunkach tlenowych na świetle, nieco słabiej w warunkach tlenowych bez dostępu światła. ß-Karoten i kapsantyna znacznie wolniej rozkładały się w warunkach próżniowych, przy czym najwolniej proces ten zachodził przy braku dostępu światła. Należy dodać, że we wszystkich wariantach przechowywania ß-karoten ulegał nieco szybszemu rozkładowi w porównaniu do kapsantyny.

13

Wplyw temperatury na parametry kinetyczne Michaelisa-Mentena ureazy glebowej

45%

Samborska A., Stepniewska Z.

Acta Agrophysica

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2000

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tom 38

165-174

Celem badań było zbadanie wpływu różnego zakresu temperatur na parametry kinetyczne Michaelisa-Mentena ureazy glebowej. Badaniom poddano próby zawierające czysty enzym (E), glebę nie nawadnianą ściekami wzbogacona enzymem (E + G) i glebę wielokrotnie nawadniana ściekami (G). Aktywność ureazową przy różnych stężeniach mocznika 0,01-3% i w różnych temperaturach: 0, 20, 37, 60°C oznaczano metodą Bonmanti i współ [I], Stałą Michaelisa (Km) i szybkość maksymalną (Vmax) wyznaczono metodą Liweavera-Burka. Aktywność ureazowa (AU) najniższa była w temperaturze 0°C, i wynosiła: 0,02 (µN-NH4 kg-1 h-1 w próbie z enzymem, 0,013 µN-NH4 kg-1 h-1 w kombinacji enzym + gleba, 0,05 (µN-NH4 kg -1h-1 w glebie irygowanej ściekami. Wraz ze wzrostem temperatury obserwowano wzrost aktywności enzymu. W temperaturze 20°C AU przedstawiała się następująco dla: E = 0,10 µN-NH4 kg-1 h-1 E + G = 0,08µN-NH4 kg-1 h -1G = 0,03 µN-NH4 kg-1 h-l. Najwyższe wartości aktywności ureazowej zanotowano w temperaturze 37°C : 0,35 µN-NH4, kg-1 h-1 dla próby zawierającej preparat handlowy, 0,16 µN-NH4 kg-1 h-l w kombinacji gleba wzbogacona enzymem, 0,125 µN-NH4 kg-1 h-1 dla gleby irygowanej ściekami miejskimi Wzrost temperatury do 60°C powodował spadek aktywności enzymatycznej. W zakresie temperatur 0-37°C zanotowano spadek wartości stałej Michaelisa i wzrost szybkości maksymalnej zachodzącej reakcji we wszystkich analizowanych wariantach, natomiast w 60°C twierdzono wzrost Km i spadek wartości Vmax. W oparciu o analizę otrzymanych wyników można stwierdzić że ureaza wykazuje największe powinowactwo względem substratu w temperaturze 37°C, natomiast wzrost temperatury jak również jej spadek zmniejsza dostępność mocznika dla enzymu.

14

Ocena parametrow kinetycznych transportu masy ksenobiotykow miedzy srodowiskiem i organizmami w zaleznosci od ich mas

45%

Zinkovsky V., Latala A., Zhuk O.

Roczniki Państwowego Zakładu Higieny

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2003

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tom 54

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nr Supl.

106-108

Ograniczanie wyników

Simplified solution of lactate dehydrogenase catalysed reaction

Application of predictive microbiological tools for assuring the health safety of food

Bio-inspired trypsin-chitosan cross-linked enzyme aggregates: a versatile approach for stabilization through carrier-free immobilization

Pyrolysis kinetics of wood comparison of iso- and polythermal thermogravimetric methods

Evaluation of mixed-salt effects on thermodynamic and kinetic parameters of RNA polymerase - promoter DNA complexes in terms of equivalent salt concentrations. General applicability to DNA complexes

Synthesis of instruments for cylindrical gear wheels rolling

Inhibition and activation of enzymes. The effect of a modifier on the reaction rate and on kinetic parameters

Kinetic characterization of beta-fructofuranosidase isolated from the bird cherry leaves

An analysis of thermal decomposition in oxidative conditions of model wood-based materials glued with amino resin

Amino acid substitutions of His296 alter the catalytic properties of Zymomonas mobilis 10232 levansucrase

Effects of early undernutrition on kinetic parameters of brain acetylcholinesterase from adult rats

Kinetic parameters of the degradative reactions of beta-carotene and capsanthin of hot red pepper stored in oxygen and vacuum atmosphere in presence or absence of light

Wplyw temperatury na parametry kinetyczne Michaelisa-Mentena ureazy glebowej

Ocena parametrow kinetycznych transportu masy ksenobiotykow miedzy srodowiskiem i organizmami w zaleznosci od ich mas