Sensitization ligands

Tpp 5,10,15,20-letraphenyl-211/,23H-porphine (ligand, sensitizer) Z electron-withdrawing groups, e.g., CHO, COR, COOR, CN, N02... 

In the case of ligand sensitization, the overall quantum yield of a lanthanide-containing molecular edifice is given by... 

The not infrequent failure of the extent of attachment of photoaffinity labels to parallel receptor inactivation can be explained in several ways. First, in some membrane-bound receptor systems, receptor subunits are present in excess over the other components of the system. Second, the ligand might induce or take part in a photochemical reaction at the ligand binding site that does not culminate in covalent attachment. Ligand sensitized photooxidation can be prevented by irradiating the sample in the... 

Owing to the unique process of ligand-sensitized lanthanide luminescence emission, the design principle of lanthanide complex-based chemosensors is distinct from that of organic chemosensors [28]. As shown in Figure 13.4, lanthanide-based luminescent chemosensors... 

Equation 2.4 combines two parameters which are typical for both the metal ion and the way the ligand is bound the parameters are called (ligand) sensitivity x and intrinsic bond stability c. c is an acronym of con-stans, alluding to the fact that this part of bonding does not depend on the electrochemical ligand parameter while the sensitivity x does. X thus refers to the iden-... 

These parameters, intrinsic bond stability c and ligand sensitivity x referring to some certain hapticity, can now be applied for calculating and thus predicting complex formation constants for all the metal ions, complex fragments and organometal species in Table 2.3... 

Binding Stability of Substrates and Products in Catalytic Cycles How Does Ligand Sensitivity Influence Reaction Kinetics ... 

Some deviation from the Irving-WUhams series results if differences of ligand sensitivities get larger than those of intrinsic bond stabilities ... 

Influence of Intrinsic Bonding Stability and Ligand Sensitivity on the Biocatalytic Properties of Metal Ions... 

As noted before, ligand sensitivities of biocata-lytically essential elements are rather close to 0 or slightly positive regardless of denticities of substrates. The other case of changing denticities between product and substrate, obeying the catalysis condition, corresponds to... 

The increased intracellular Ca2+ concentration also has an inhibitory effect, which eventually shuts down the signal. The ion binds to calmodulin (CaM) lowering the ligand sensitivity of the cAMP-gated channels and activating the activity of a phosphodiesterase (PDE). Ca2+ is finally extruded by a Na+/Ca2+ exchanger. 

The ZP3-dependent cation channel, an essential component of the signaling cascade, cannot be activated in uncapacitated sperm. Ligand sensitivity is acquired as an early event in capacitation (Florman, 1994). 

Of special interest for the topic of the present chapter is the observation of Weaver that while the double-layer-corrected AS quantities are ligand sensitive, they are found to be independent of potential. This is not the case for the atom and electron transfer process involved in the hydrogen evolution reaction at Hg studied by Conway, et where an appreciable potential dependence of AS is observed, corresponding to conventionally anomalous variation of the Tafel slope with temperature. Unfortunately, in the work with the ionic redox reactions, as studied by Weaver, it is only possible to evaluate the variation of the transfer coefficient or symmetry factor with temperature with a limited variety of redox pairs since Tafel slopes, corresponding to any appreciable logarithmic range of current densities, are not always easily measurable. Alternatively, evaluation of a or /3 from reaction-order determination requires detailed double-layer studies over a range of temperatures. 

From ligand sensitization to translation of genes, every single process in cells is dependent on the intracellular levels and activity of various signaling molecules and pathways. These signaling events lead to very critical posttranslational modifications such as phosphorylation, sumoylation, ubiquitination and others that are... 

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