Michaelis-Menten data

The thermal polymer was inhibited by diisopropyl iluorophosphate (DFP Table V). The extent of inhibition was dependent upon the length of preincubation of polymer with DFP (20 mg of polymer per micromole of DFP) and was, e.g., 80% after 6 hoiurs of preincubation. The inhibition by DFP could be 80% reversed by 0.1 il/ 1,3-bis(iV-pyridinium aldoxime)propane. The authors conclude that the inhibition, reactivation, and Michaelis-Menten data obtained are indicative of enzyme-like properties. 

TABLE 2.3. Error-Free Michaelis-Menten Data for Method of Comparison... 

The parameters of the Monod cell growth model are needed i.e. the maximum specific growth rate and the Michaelis-Menten constant are required for a suitable rate equation. Based on the data presented in Tables 10.1 and 10.2, obtain kinetic parameters for... 

Kinetic data fitting the rate equation for catalytic reactions that follow the Michaelis-Menten equation, v = k A]/(x + [A]), with[A]0 = 1.00 X 10 J M, k = 1.00 x 10 6 s 1, and k = 2.00 X 10-J molL1. The left panel displays the concentration-time profile on the right is the time lag approach. 

According to this expression, a plot of 1/v, versus l/[SJo will yield a straight line if the data follow the Michaelis-Menten mechanism. This line has a slope given by Km/Vmax, a y intercept of 1/Vmax, and an x intercept of -1 fKm. This is also illustrated in Fig. 4-7. Again, this treatment is valid when Eq. (4-107) applies whether or not the catalyst is an enzyme. The Lineweaver-Burk plot, Fig. 4-lb, is convenient for visualization but statistically unreliable for data fitting the form in Eq. (4-107) should be used for numerical analysis. 

Enzyme kinetics. Data for reactions that follow the Michaelis-Menten equation are sometimes analyzed by a plot of v,/tA]o versus l/[A]o. This treatment is known as an Eadie-Hofstee plot. Following the style of Fig. 4-7b, sketch this function and label its features. 

The direct measurement of the numeric value of and therefore the calculation of often requires im-practically high concentrations of substrate to achieve saturating conditions. A linear form of the Michaelis-Menten equation circumvents this difficulty and permits and to be extrapolated from initial velocity data obtained at less than saturating concentrations of substrate. Starting with equation (29),... 

On the other hand, the macrolides showed unusual enzymatic reactivity. Lipase PF-catalyzed polymerization of the macrolides proceeded much faster than that of 8-CL. The lipase-catalyzed polymerizability of lactones was quantitatively evaluated by Michaelis-Menten kinetics. For all monomers, linearity was observed in the Hanes-Woolf plot, indicating that the polymerization followed Michaehs-Menten kinetics. The V, (iaotone) and K,ax(iaotone)/ m(iaotone) values increased with the ring size of lactone, whereas the A (iactone) values scarcely changed. These data imply that the enzymatic polymerizability increased as a function of the ring size, and the large enzymatic polymerizability is governed mainly by the reachon rate hut not to the binding abilities, i.e., the reaction process of... 

In kinetic studies of enzymatic reactions, rate data are usually tested to determine if the reaction follows the Michaelis-Menten model of enzyme-substrate interaction. Weetall and Havewala [Biotechnol. and Bioeng. Symposium 3 (241), 1972] have studied the production of dextrose from cornstarch using conventional... 

Because the amounts and density of these transporters vary along the gastrointestinal tract, it is necessary to introduce a correction factor for the varying transport rates in the different luminal and enterocyte compartments. Due to the lack of experimental data for the regional distribution, and Michaelis-Menten constants for each drug in Table 18.2, we fitted an intrinsic (concentration-independent) transport rate for each drug to closely approximate the experimental %HIA. This... 

The kinetic data from phosphate [28] and proton [58] release experiments were analyzed quantitatively by means of a modified Michaelis-Menten equation assuming activation when only one substrate molecule, S, is bound and inhibition when two substrate molecules are bound to P-gp as described by the following scheme ... 

Figure 8 Plot of the initial rate of the enzyme-catalyzed oxidation of 1-phenylpropanol as a function of % ee. The solid line represents a fit of the data to the Michaelis-Menten formalism for competitive inhibition where [S] = [ -(60)] and [ ] = [ -(60)]. The total alcohol concentration was maintained constant at lOmM.100...

Fig. 1 a and b show how the Andrews and the Michaelis-Menten functions (with the optimal parameter values) respectively fit the experimental data... 

TO AVOID CURVED PLOTS there are several ways to rearrange the Michaelis-Menten equation so that data can be plotted to give a straight line. The slope and intercepts give you values for Km and Vmax or give you values from which Km and Vmax can be calculated. 

The problem is that substrate conversions are frequently lower than 10% and thus difficult to detect in most traditional formats. As previously discussed in this chapter, /iPLC allows optimal operation even when working with low substrate conversion (e.g., as low as 1% as described by Wu et al.12). Data obtained allow the calculation of the Michaelis-Menten constant (Km) for ATP. An example of such an evaluation is presented in Figure 6.48 in which the obtained reaction velocities... 

The phosphorylation of each substrate was monitored via a one- or two-substrate reaction in real time and the kinetic parameters (Vmca, Km, kcat, and kcJKm) were determined. Figure 6.54 shows the results of the evaluations of velocity with respect to substrate (Kemptide and CREBtide) concentrations. The data were fitted using the Michaelis-Menten equation to determine the kinetic parameters shown in Table 6.8. The V , of phosphor-Kemptide (105.57 pM/min) was approximately 4.3-fold larger than the V , for CREBtide (24.33 pM/min) although both peptide substrates had similar... 

In principle, the differential form (Eq. (1)), as well as the integrated form (Eq. (8)), can be used. The differential form of the Michaelis-Menten equation is applied in many cases, since differential values (e.g., flow meter or heat flow data) are often available by contrast, time-dependent substrate or product concentrations (or proportional quantities) can easily be differentiated numerically. 

Introduction 257 The Basics of Michaelis-Menten Kinetics 259 Hydrogenation From a Kinetic Viewpoint 263 Measurement of Concentration-Time Data and Possible Problems 263... 

Hydrolysis of methyl hydrocinnamate is catalyzed by the enzyme chymotripsin. Data were obtained at 25 C with pH k7.6 and a constant enzyme concentration. These are of initial reaction rate, mol/1iter-sec, and corresponding initial substrate concentrations. Find the Michaelis-Menten constants. 

Use the data in Table 2.2 to plot Michaelis-Menten, Lineweaver-Burke and Eadie-Hofstee graphs to determine Km and Vm DC values. Answers are given at the end of the chapter. 

There are many ways to measure the concentrations of reacting species or species formed during the reaction, such as there are gc, UV-visible spectroscopy, IR spectroscopy, refiactometry, polarometry, etc. Conversion can be monitored by pressure measurements, gas-flow measurements, calorimetry, etc. Data are collected on a computer and many programmes are available for data analysis [3,4], The two-reaction system described above can be treated graphically, if it fulfils either the Bodenstein or Michaelis-Menten criteria. 

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