Michaelis-Menton plot

Fig. 5. Michaelis-Menton plot of o against o/S (V against V/S in figure) for acetylcholinesterase (AChE) and cholinesterase (BChE) using acetylcholine as substrate. (After Main, M3.)...

Figure 5. Silica precipitating activity of R5 determined using the fi -silicomolybdate method. Data plotted as a (a) Michaelis Menton plot, (b) Lineweaver — Burke plot.

In this scheme, EOH is the enzyme, IX is the inhibitor (either a carbamate or an organophosphate). EOH(IX) is analogous to the Michaelis Menton comploc seen with the substrate reaction. EOI is the acyl-enzyme intermediate for carbamates or a phosphoro-enzyme intermediate for the organophosphates. The equilibrium constant for this reaction (K ) is defined as k /k and the phosphorylation or carbamylation constant is defined as k2- In this study 42)y ANTX-A(S) was found to be more specific for AChE than BUChE. The double reciprocal and Dixon plot of the inhibition of electric eel AChE indicated that the toxin is a non-competitive inhibitor decreases, k remains unchanged) (Figure 2). 

The cytochrome P-450-dependent metabolism of trichloroethylene was studied in hepatic microsomal fractions from 23 different humans (Lipscomb et al. 1997). CYP2E1 was the predominant form of P-450 responsible for the metabolism of trichloroethylene in humans. Incubations of trichloroethylene with the microsomal preparations resulted in hyperbolic plots consistent with Michaelis-Menton kinetics. The values ranged from 12 to 55.7 pM, and were not normally distributed, and the values range from 490 to 3,455 pmol/min/mg protein and were normally distributed. The study authors concluded that the human variability in metabolism of trichloroethylene via P-450-dependent pathways was within a 10-fold range. 

Kinetic studies of this reaction have shown that it obeys Michaelis-Menton kinetics as expressed by the Lineweaver-Burk plot, the Michaelis constant (KJ for this reaction at pH 7.0 and 37.5 °C being 2.86 x 10 4 M 24). Free lysine, Leuehs Poly-L-lysine, total hydrolyzates of thermal polylysine, and amino group-modified thermal polylysine are completely inactive. The activity of thermal polylysine depends on the degree of polymerization 24). 

From the Lineweaver-Burk plot, the data do conform to the Michaelis-Menton rate law and... 

Evaluation of the polymer s catalytic activity involved monitoring hydrolysis reactions using 50-fold molar excess of 23 with respect to the theoretical amount of functional groups present in each polymer. Figure 4 shows a plot of percent hydrolysis vs. time. Curves a, b, and c correspond to polymers P-12, P-13, and P-11, respectively. It is clear that curves a and b do not display a typical pseudo first-order kinetics. Only curve c displays Michaelis-Menton kinetics, indicating P-11 contains an active site that may bear some features of saturation kinetics (Table 5) wherein cooperative effects from juxtaposed ligands help to enhance the nucleophilicity of the serine-hydroxyl group (Scheme 12). 

This equation is known as the Michaelis-Menton equation. A plot of rate r versus substrate concentration [S] (Figure 2.20) shows that the rate equation follows first-order kinetics fp = (k/kuAS] at low substrate concentrations and zero-order kinetics r = k ed. high substrate concentrations. The tangent to versus [S] plot drawn at [S] = 0 intersects r = k at a point corresponding to [S] = k - This method of tangent can be used to determine the kinetic parameters k and k - Alternatively, we can write the rate equation in linear form as (l/fp) = kM/k) l/[S]) + (1/k) by inverting Equation 2.169. Thus, by making a linear plot of... 

Figure 9.32 displays the amperometric response at -200 mV for HRP/MW-CNT200/PS biocomposite sensor to H2O2. A linear response is found in the H2O2 concentration range of 0.02-0.5 luM and Ae detection limit is 25 pM. The apparent Michaelis-Menton constant is calculated from the inserted linear plot to be... 

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