Lineweaver-Burk kinetic

The effects of these classes of inhibitors on Lineweaver-Burk kinetics are shown in Figures 1-8-7 and 1-8-8. Notice that on a Lineweaver-Burk graph, inhibitors always lie above the control on the right side of the y-axis. A line below the control might represent the addition of an activator. 

This equation corresponds to the Lineweaver-Burk kinetic equation (Lyons et al., 1992, 1994) and can be transformed into an equation giving the dependence of kinetic currents, 4, on the concentration of substrate in the solution bulk. Values of /), at different concentrations of substrate can be determined from the limiting, steady-state currents, tht.i, obtained, for instance, as plateau currents in rotating disk voltammetry, using Equation (3.6). For the case of thin films with a surface concentration of catalytic centers (rnol/crn ) over an electrode of area A, one can write ... 

Here, the mode of Zn action against the REE-induced OXB was assessed with Lineweaver-Burk kinetics and possible eco-physiological roles for Zn in interaction with other metal cations in plants are discussed. 

For Lineweaver-Burk kinetic analysis, the reciprocals of CLA-CL yield (1/rcu) were plotted as function of the reciprocals of La cone. (l/[La ). Data in the absence and presence of Zn graphically analyzed. 

The three reversible mechanisms for enzyme inhibition are distinguished by observing how changing the inhibitor s concentration affects the relationship between the rate of reaction and the concentration of substrate. As shown in figure 13.13, when kinetic data are displayed as a Lineweaver-Burk plot, it is possible to determine which mechanism is in effect. 

Lineweaver-Burk plot a graphical means for evaluating enzyme kinetics, (p. 638)... 

Lineweaver-Burk plot Method of analyzing kinetic data (growth rates of enzyme catalyzed reactions) in linear form using a double reciprocal plot of rate versus substrate concentration. 

The Michaelis-Menten equation is, like Eq. (3-146), a rectangular hyperbola, and it can be cast into three linear plotting forms. The double-reciprocal form, Eq. (3-152), is called the Lineweaver-Burk plot in enzyme kinetics. ... 

First draw both Lineweaver-Burk plots and Hanes-Woolf plots for the following a Monod-Wyman-Changeux allosteric K enzyme system, showing separate curves for the kinetic response in (1) the absence of any effectors (2) the presence of allosteric activator A and (3) the presence of allosteric inhibitor I. Then draw a similar set of curves for a Monod-Wyman-Changeux allosteric Uenzyme system. 

Fig. 39.17. Schematic illustration of Michaelis-Menten kinetics in the absence of an inhibitor (solid line) and in the presence of a competitive inhibitor (dashed line), (a) Plot of initial rate (or velocity) V against amount (or concentration) of substrate X. Note that the two curves tend to the same horizontal asymptote for large values of X. (b) Lineweaver-Burk linearized plot of 1/V against l/X. Note that the two lines intersect at a common intercept on the vertical axis.

In our previous work [63], we studied the hydrolysis kinetics of lipase from Mucor javanicus in a modified Lewis cell (Fig. 4). Initial hydrolysis reaction rates (uri) were measured in the presence of lipase in the aqueous phase (borate buffer). Initial substrate (trilinolein) concentration (TLj) in the organic phase (octane) was between 0.05 and 8 mM. The presence of the interface with octane enhances hydrolysis [37]. Lineweaver-Burk plots of the kinetics curve (1/Uj.] = f( /TL)) gave straight lines, demonstrating that the hydrolysis reaction shows the expected kinetic behavior (Michaelis-Menten). Excess substrate results in reaction inhibition. Apparent parameters of the Michaelis equation were determined from the curve l/urj = f /TL) and substrate inhibition was determined from the curve 1/Uj.] =f(TL) ... 

Engine Kinetics Results from the Lineweaver-Burk transformation. 

The enzymatic activities of intercalated GOx-AM P layered nanocomposites at various pH values and temperatures were compared with the native enzyme in aqueous solution. In both cases, characteristic linear plots consistent with Michalis-Menton kinetics were obtained. The Lineweaver-Burk plots indicated that the reaction rates (Vmax) for free and intercalated GOx (3.3 and 4.0 pM min 1 respectively), were comparable, suggesting that the turnover rate at substrate saturation was only marginally influenced by entrapment between the re-assembled organoclay sheets. However, the dissociation constant (Km) associated with the activity of the enzyme was higher for intercalated GOx (6.63 mM) compared to native GOx (2.94 mM), suggesting... 

Determine the kinetics parameters Km and Vmax, assuming that the standard Michaelis-Menten model applies to this system, (a) by nonlinear regression, and (b) by linear regression of the Lineweaver-Burk form. 

An analysis of the influence of errors shows clearly that the double-reciprocal plot according to Lineweaver-Burk [32] is the least suitable. Although it is by far the most widely used plot in enzyme kinetics, it cannot be recommended, because it gives a grossly misleading impression of the experimental error for small values of v small errors in v lead to enormous errors in 1/y but for large values of v the same small errors in v lead to barely noticeable errors in 1/17 [23]. Due to the error distribution, that is much more uniform, the plot according to Hanes (Eq. (7)), is the most favored. 

Characteristically, within certain concentration limits, if a chemical is absorbed by passive diffusion, then the concentration of toxicant in the gut and the rate of absorption are linearly related. However, if absorption is mediated by active transport, the relationship between concentration and rate of absorption conforms to Michaelis-Menten kinetics and a Lineweaver-Burk plot (i.e., reciprocal of rate of absorption plotted against reciprocal of concentration), which graphs as a straight line. 

Schultz s group employed an a-hydroxyphosphonate hapten [99] and subsequently isolated 20 cell lines of which 5 catalysed the hydrolysis of the model substrate p-nitrophenyl phosphate [100] above background (Fig. 34) (Scanlan et al., 1991). Antibody 38E1 was characterized in more detail and kinetic parameters were afforded by Lineweaver-Burke analysis. This antibody exhibited 11 turnovers per binding site with no change in Vmax, and thus acted as a true catalyst. Moreover, examination of substrate specificity showed that catalysis was entirely selective for p-substituted species (Appendix entry 6.6). 

Enzyme kinetics Michaelis constant, symbol iCm maximum velocity of an enzyme catalysed reaction, Vm DC inhibitor constant, symbol X Michaelis-Menten equation and graph in the absence and the presence of inhibitors. Lineweaver-Burke and Eadie-Hofstee plots. 

The apparent kinetic constants were obtained from Lineweaver-Burk plots of AHH activities recorded in the presence of increasing concentrations of benzo(a)pyrene (0.001-1.0 mM). The plots were linear for both untreated and DBA-induced animals. The apparent V was 20- to 30-fold higher in hepatic microsomes from the induced skates whereas the apparent K values were of the same magnitude in control and treated fish. 

The kinetic characteristics of this reaction were studied according to the procedure descrihed in Section 3.3.1.4. The results obtained are presented in Figure 4.54 in terms of Lineweaver-Burk reciprocal plots. The intercepts and slopes of the tines shown in Figure 4.54 are plotted in Figure 4.55. 

First, the activity of the enzyme was measured and kinetic parameters were determined by Lineweaver-Burk plots, using phenyhnalonic acid as the substrate. The results are summarized in Tabled. Among four mutants, C188S showed a drastic decrease in the activity (k -jt/Kn,). The low activity was due to a decrease in the catalytic tirrnover number (k(.jt) rather than in affinity for the substrate (Km). 

We examined the effect of restricted conformation on the activation entropy by kinetic studies at various temperatures [34]. Three kinds of substrates were subjected to the reaction phenylmalonic acid as the standard compound, ortho-chlorophenylmalonic acid as a substrate with an electron-withdrawing group, and indane-l,l-dicarboxylic acid as a conformationally restricted compound. The initial rates of the enzymatic decarboxylation reaction of three compounds were measured at several substrate concentrations at 15 °C, 25 °C, and 35 °C. The kcat and values at each temperature were obtained by a Lineweaver-Burk plot,... 

Kinetics of Bound and Free Enzyme. The kinetics of the IME were obtained with the recirculating differential reactor system as described above. The appropriate flow rate, the temperature optimum, and pH optimum as described above were used to most accurately establish the kinetic parameters for this IME emgmie. Substrate solutions from 3 to 150 mM cellobiose in 10 mM sodium acetate were appropriate for this portion of the study. Results were analyzed with the ENZFTT software package (Elsevier Publishers) that permits precise Lineweaver-Burk regressions. 

Kinetics of Free and Mao-osoib-Bound eaiymc. The results of the Lineweaver-Burk analysis of the initial rates for free and immobilized enzyme appear in Table I. The increase in the substrate affinity parameter due to some internal mass transfer limitations in the IME as no substrate-matrix interactions were present. The increase... 

The main plots used in enzyme kinetics and receptor binding studies are the Scatchard plot, the Lineweaver-Burk plot, and the linearization for estimation of the Hill coefficient. This chapter gives a short survey of these transformations of enzyme kinetics or receptor binding data. 

Figure 8.4 The Lineweaver-Burk plot (A) and the Hanes plot (B) of typical enzyme kinetics in presence of a competitve (a) noncompetive (b), mixed type (c) and uncompetitive (d) inhibitor.

Lineweaver-Burk analysis using the substrate saturation curves afforded the corresponding Michaelis-Menten kinetic parameters of the reaction V max=l-79 xIO- Ms , KM=21.5mM, kcat = 8.06x 10 s for 69, and Knax = 9.22x 10... 

Figure 3.6 Evaluation of kinetic parameters in Michaelis-Menten equation (a) Lineweaver-Burk plot, (b) C /r versus plot, and (c) Eadie-Hofstee plot.

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