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Wyszukujesz frazę "enzyme kinetics" wg kryterium: Temat

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    Wyświetlanie 1-8 z 8
    Tytuł:
    An easy procedure to transform the ratio of two polynomials of first degree into Michaelis-Menten-type equations. Application to the ordered Uni Bi enzyme mechanism.
    Autorzy:
    Fontes, Rui
    Ribeiro, João
    Sillero, Antonio
    Powiązania:
    https://bibliotekanauki.pl/articles/1044439.pdf
    Data publikacji:
    2000
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    rectangular hyperbolas
    enzyme inhibition
    enzyme equations
    enzyme kinetics
    graphical presentations
    Opis:
    It is not always clear that some equations affected by complicated factors can, actually, be interpreted as a ratio of two polynomials of first degree and so that they can be, in general, represented by rectangular hyperbolas. In this paper we present an easy procedure to rearrange those equations into Michaelis-Menten-type equations and so to make the aspects of these rectangular hyperbolas more clear, particularly for researchers familiar with general biochemistry. As an example, the method is applied to transform the classical rate equation of the Cleland×s Ordered Uni Bi enzyme mechanism.
    Źródło:
    Acta Biochimica Polonica; 2000, 47, 1; 259-268
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mathematical modeling to optimize the product in enzyme kinetics
    Autorzy:
    Nandi, S.
    Ghosh, M. K.
    Bhattacharya, R.
    Roy, P. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/206501.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    enzyme kinetics
    optimization
    optimal control approach
    reversible reaction
    Opis:
    Optimization of product in enzyme kinetics is successful by the showers of mathematical analysis with control measures. Enzymes are an important functional aspects of all biochemical processes, as they catalyze numerous reaction taking place within living organisms. With this view, optimization and quantification of product is stressed upon and in such a context, optimal control approaches have been applied in our study. In this article, we have formulated a mathematical model of enzymatic system Dynamics with control measures with a view to optimize the product as well as process conditions. Here, Pontryagin Minimum Principle is used for determination of optimal control with the help of Hamiltonian. We discuss the relevant numerical solutions for the concentration of substrate, enzyme, complex and product with respect to a specified time interval by varying control factors.
    Źródło:
    Control and Cybernetics; 2013, 42, 2; 431-442
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Inhibition and activation of enzymes. The effect of a modifier on the reaction rate and on kinetic parameters.
    Autorzy:
    Fontes, Rui
    Ribeiro, João
    Sillero, Antonio
    Powiązania:
    https://bibliotekanauki.pl/articles/1044438.pdf
    Data publikacji:
    2000
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    enzyme inhibition
    enzyme modifier
    rapid equilibrium kinetics
    I50
    enzyme activation
    enzyme kinetics
    graphical presentations
    Opis:
    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 = Ł([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.
    Źródło:
    Acta Biochimica Polonica; 2000, 47, 1; 233-257
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Contribution of the intra- and intermolecular routes in autocatalytic zymogen activation: application to pepsinogen activation
    Autorzy:
    Varón, Ramón
    Fuentes, Matilde
    García-Moreno, Manuela
    Garcìa-Sevilla, Francisco
    Arias, Enrique
    Valero, Edelmira
    Arribas, Enrique
    Powiązania:
    https://bibliotekanauki.pl/articles/1041258.pdf
    Data publikacji:
    2006
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    intermolecular activation
    intramolecular activation
    autocatalysis
    enzyme kinetics
    proenzyme activation
    Opis:
    Taking as the starting point a recently suggested reaction scheme for zymogen activation involving intra- and intermolecular routes and the enzyme-zymogen complex, we carry out a complete analysis of the relative contribution of both routes in the process. This analysis suggests the definition of new dimensionless parameters allowing the elaboration, from the values of the rate constants and initial conditions, of the time course of the contribution of the two routes. The procedure mentioned above related to a concrete reaction scheme is extrapolated to any other model of autocatalytic zymogen activation involving intra- and intermolecular routes. Finally, we discuss the contribution of both of the activating routes in pepsinogen activation into pepsin using the values of the kinetic parameters given in the literature.
    Źródło:
    Acta Biochimica Polonica; 2006, 53, 2; 407-420
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Kinetic analysis of the transient phase and steady state of open multicyclic enzyme cascades
    Autorzy:
    Varón, Ramón
    Havsteen, Bent
    Valero, Edelmira
    Molina-Alarcón, Milagros
    García-Cánovas, Francisco
    García-Moreno, Manuela
    Powiązania:
    https://bibliotekanauki.pl/articles/1041315.pdf
    Data publikacji:
    2005
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    steady state
    fractional modification
    transient phase
    enzyme kinetics
    multicyclic cascades
    Opis:
    This paper presents a kinetic analysis of the whole reaction course, i.e. of both the transient phase and the steady state, of open multicyclic enzyme cascade systems. Equations for fractional modifications are obtained which are valid for the whole reaction course. The steady state expressions for the fractional modifications were derived from the latter equations since they are not restricted to the condition of rapid equilibrium. Finally, the validity of our results is discussed and tested by numerical integration. Apart from the intrinsic value of knowing the kinetic behaviour of any of the species involved in any open multicyclic enzyme cascade, the kinetic analysis presented here can be the basis of future contributions concerning open multicyclic enzyme cascades which require the knowledge of their time course equations (e.g. evaluation of the time needed to reach the steady state, suggestion of kinetic data analysis, etc.), analogous to those already carried out for open bicyclic cascades.
    Źródło:
    Acta Biochimica Polonica; 2005, 52, 4; 765-780
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optimal control of a fractional-order enzyme kinetic model
    Autorzy:
    Al-Basir, F.
    Elaiw, A. M.
    Kesh, D.
    Roy, P. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/206336.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Instytut Badań Systemowych PAN
    Tematy:
    enzyme kinetics
    cooperative phenomenon
    fractional derivative
    mathematical modeling
    Hamiltonian
    optimal control problem
    Opis:
    Enzymes play a significant role in controlling the characteristics of various chemical and biochemical reactions. They act as catalysts that increase the rate of reaction without undergoing any change in quantity. Enzymatic reactions occur through the active sites, which combine with the substrates to form intermediate complexes, subsequently leading to products. An enzyme having two active sites can show cooperative phenomena. Against this background, an enzyme-kinetic mathematical model is formulated using fractional order derivatives. Optimal control mechanism has been incorporated into the fractional-order model system to maximize the product output. Euler-Lagrange optimality conditions are derived for the FOCP (fractional order control problem) using maximum principle. Numerical iterative schemes have been developed to solve the fractional order optimal control problem through Matlab.
    Źródło:
    Control and Cybernetics; 2015, 44, 4; 443-461
    0324-8569
    Pojawia się w:
    Control and Cybernetics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    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:
    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 1-8 z 8

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