Saturation function

Subsequently Briggs and Haldane (1925) demonstrated that a similar treatment could be used to describe steady state enzyme velocity as a saturable function of substrate concentration ... 

For the enzyme isomerization mechanism illustrated in scheme C of Figure 6.3, there are two steps involved in formation of the final enzyme-inhibitor complex an initial encounter complex that forms under rapid equilibrium conditions and the slower subsequent isomerization of the enzyme leading to the high-affinity complex. The value of kohs for this mechanism is a saturable function of [/], conforming to the following equation ... 

Figure 1.1 A simple model of gene expression. The model has been implemented and simulated in the program Gepasi.41 42 Nonlinear saturable functions chosen for the kinetics of all 6 reactions and parameter values chosen to produce extreme behaviors (details available from authors).

What would be the corresponding behavior of an enzyme obeying the Michaelis-Menten model For the answer, let us restate the Michaelis-Menten model in the form of a saturation function ... 

If a macromolecule engages in two different association reactions with ligands X and Y at nearby (or structurally linked) binding sites, there arises the likelihood that the binding functions for these ligands will exhibit an interdependence that stems from the interaction between these sites. Such sites are said to be linked, and the saturation function describing their binding interactions is called a linked function. 

The ligand saturation function accounts for the moles of bound... 

Reduced concentrations are also useful in the Monod-Wyman-Changeux cooperativity model, where a = [F]/ Kj and ca = [F]/X t. This makes polynomial functions simpler to handle. For example, if ligand F binds exclusively to the R-state, then the ligand F saturation function, Tf, for an n-site protein equals (1 + +... 

What about the likely case that there are two classes of binding interactions—one strong and one weak To treat this case, we write two separate saturation functions, one for each class of sites ... 

A procedure used in the characterization of cooperative proteins in which the second moment of the derivative of the saturation function is measured. 

SARCOSINE DEHYDROGENASE SARCOSINE OXIDASE SATURATION Saturation function,... 

Stereoisomerism Substituents Parent Un saturation Functional group... 

Calibration is necessary for in-situ spectrometry in TLC. Either the peak height or the peak area data are measured, and used for calculation. Although the nonlinear calibration curve with an external standard method is used, however, it shows only a small deviation from linearity at small concentrations [94.95 and fulfils the requirement of routine pharmaceutical analysis 96,97J. One problem may be the saturation function of the calibration curve. Several linearisation equations have been constructed, which serve to calculate the point of determination on the basis of the calibration line and these linearisation equations are used in the software of some scanners. A more general problem is the saturation function of the calibration curve. It is a characteristic of a wide variety of adsorption-type phenomena, such as the Langmuir and the Michaelis-Menten law for enzyme kinetics as detailed in the literature [98. Saturation is also evident for the hyperbolic shape of the Kubelka-Munk equation that has to be taken into consideration when a large load is applied and has to be determined. 

Masalmeh, S.K., 2002. The effect of wettability on saturation functions and impact on carbonate reservoirs in the Middle East. Paper SPE 78515 presented at Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, 13-16 October. 

Pepperberg DR, Birch DG, Hofmann KP, et al. Recovery kinetics of human rod phototransduction inferred from the two-branched a-wave saturation function. J Opt Soc Am A 1996 13 586-600. 

In order to utilize the saturation functions derived for pure feed and pure resin, a solution saturation-fraction must be defined,... 

J mathematical solution for column-saturation function gives x at r = 1... 

Maximum crop loss per day. The relationship between number of sporulating lesions and crop damage is modeled as a saturation function, and this represents the proportion of the crop loss per day at the saturation lesion count. 

Figure 6.33. Theoretical dependence of the saturation function (eq. 6.71 with n=4).

Figure 5.30b shows again, on a larger scale, the variation of extracellular cAMP. Also represented in this figure are the variation of the total fraction of receptor in the desensitized state (Sp), and the receptor saturation function (T). This function, defined by relation (5.13), takes into account the binding of cAMP to the two forms of the receptor ... 

The phase difference between the saturation function of the receptor and extracellular cAMP depends on the value of parameter c, which measures the relative affinity of the ligand for the two receptor states. A negligible phase shift should be observed as long as the R state possesses a higher affinity for cAMP (c < 1) in the opposite case, the saturation function should reach its maximum after the peak in cAMP. A detailed experimental study, not yet available, would permit us to obtain information on that point and could indirectly )neld indications as to the value of coefficient c. The curves in fig. 5.30a and b also show that for the parameter values chosen (and, in particular, for c = 10), the maximum of the fraction of active, dephosphorylated receptor shortly precedes the maximum in cAMP, while the increase in the fraction of desensitized receptor follows the peak in cAMP. 

Fig. 5.30. Sustained oscillations of cAMP in the model based on receptor desensitization. (a) The evolution of intracellular cAMP (/3), ATP (a), the total fraction of receptor in active state (pr), and extracellular cAMP (-y). The latter is represented, on an enlarged scale, in (b) together with the total fraction of receptor in the desensitized state (Sp) and the saturation function (Y) measuring binding of cAMP to the two receptor states. The curves are obtained by numerical integration of the four-variable system (5.9) for the parameter values indicated in table 5.3 most of these values are those determined experimentally and available in the literature (see table 5.2). Similar curves are obtained by integration of the three-variable system (5.12) when ATP is maintained constant at the value a = 3 (Martiel Goldbeter, 1987a).

The existence of the abrupt threshold for the relay response is linked to the excitable properties of the cAMP-synthesizing system. Like the oscillations, excitability is due mainly to the self-amplifying nature of cAMP production in the slime mould. As indicated by the curve yielding the saturation function of the receptor as a function of the cAMP signal in fig. 5.32, no threshold is detectable for binding of the ligand to... 

Fig. 5.32. Existence of a threshold for the relay of cAMP signals. The amplitude of the response, measured by the ratio of the maximum of the peak of intracellular cAMP divided by the steady-state level of /3, is represented as a function of the initial value of extracellular cAMP divided by the steady-state level of y, under the conditions of fig. 5.31. The dose-response curve for the synthesis of cAMP possesses an abrupt threshold. In contrast, no threshold is apparent in the saturation function of the cAMP receptor, Y (Martiel Goldbeter, 1987a).

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