Binding isotherm equation

Fractional velocity as a function of inhibitor concentration, as illustrated in Figure 5.2, can be fit to a simple binding isotherm equation (see Appendix 2) ... 

Derivation of the Enzyme-Ligand Binding Isotherm Equation... 

Note that Equations (A2.14) and (A2.18) do not take into account any influence of substrate concentration on the apparent value of Kd. As described in Chapter 5, this can be accounted for most generally by replacing the term Kd in these equations with the observed value of Kfp or IC50. Making this substitution in Equation (A2.18), we obtain the binding isotherm equation that has been used throughout this book ... 

Both binding isotherm (Equation 8.15) and double-reciprocal plots (Equation 8.16) are expressed as a function of free ligand concentration, which is not known. By means of the mass balance on ligand,L can be related to the known total ligand concentration... 

Usually non-cooperative and non-Unear binding isotherms were observed in alkaloid-B-DNA complexation and the data were fitted to a theoretical curve drawn according to the excluded site model [126] developed by McGhee and von Hippel [127] for a non-Unear non-cooperative ligand binding system using the following equation ... 

In the mechanism illustrated by scheme B, significant inhibition is only realized after equilibrium is achieved. Hence the value of vs (in Equations 6.1 and 6.2) would not be expected to vary with inhibitor concentration, and should in fact be similar to the initial velocity value in the absence of inhibitor (i.e., v, = v0, where v0 is the steady state velocity in the absence of inhibitor). This invariance of v, with inhibitor concentration is a distinguishing feature of the mechanism summarized in scheme B (Morrison, 1982). The value of vs, on the other hand, should vary with inhibitor concentration according to a standard isotherm equation (Figure 6.5). Thus the IC50 (which is equivalent to Kfv) of a slow binding inhibitor that conforms to the mechanism of scheme B can be determined from a plot of vjv0 as a function of [/]. 

THE CONNECTION BETWEEN THE KINETIC EQUATION AND THE BINDING ISOTHERM... 

Equation (8.2.5) establishes the connection between the rate of the enzymatic reaction within the steady-state approximation, and the equilibrium binding isotherm. 

Selected entries from Methods in Enzymology [vol, page(s)] Additive properties of polarization, 246, 286 angle-resolved, assessment of peroxidation effects on membranes, 233, 274-275, 281-283, 287-288 binding isotherm construction, 246, 287-288 effect of inner filter effects, 246, 288 incoherent systems, 246, 263-264 orientational averaging, 246, 265, 269-270 Perrin equation, 246, 284-285 polarization of emission, 246, 284 rotational diffusion, 246, 9, 260 time-resolved, assessment of peroxidation effects on membranes, 233, 274, 283-285, 285-287. 

EYRING EQUATION BINARY COMPLEX MICHAELIS COMPLEX BINDING CHANGE MECHANISM BINDING INTERACTION ALLOSTERIC INTERACTION BINDING ISOTHERM BIOSENSOR... 

Applequist, J. (1977) J. Chem. Ed. 54,417]. Show from the equation for the binding isotherm that the following equation holds at Y = 1 / 2 ... 

Equation 8.15 is the binding isotherm, which shows the hyperbolic dependence of absorbance on free ligand concentration. 

This equations expresses the dependence of a bound reagent [AB] (once again, in the case of 1 1 binding it is equal to the amount of complex in equilibrium) versus free reagent [B], Plotting [AB] versus [B] results in a typical binding isotherm with hyperbolic shape. The double-reciprocal form of the binding isotherm,... 

In formulating adsorption Isotherm equations, assumptions have to be made about the kinds of ions that bind, and on the planes where they adsorb. Stem himself considered the specific adsorption of cations and anions, both at the outer Helmholtz plane (approximation (li) in the previous subsection)More likely are situations where only one ionic type adsorbs at the inner Helmholtz plane. For that case, the Langmuir equation is readily extended. We start with IA1.2al, which we write as 6J( -Q ) = K x. Here, = is the ratio... 

If we can assume that the reaction of counterion binding is much faster than the surfactant adsorption, then we can set Q2 = 0, and Equation 5.56 reduces to the Stem isotherm (Equation 5.47), with A 2= 2ads/ 2des- Next, a substitution of E2 from Equation 5.47 into Equation 5.53 yields ... 

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