Ligand-like adsorption

Adsorptive endocytosis occurs when a glycoprotein on the brain s endothelial surface binds another glycoprotein in ligand like fashion (Broadwell et al., 1988 Broadwell, 1989). This second glycoprotein (the ligand) may be free or attached to the snrface of a virus or immune cell (Mellman et al., 1986). The binding can initiate endocytosis with the snbseqnent vesicle having several potential fates (Banks and Broadwell,... 

Deuterium might adsorb by heterolytic ligand displacement adsorption at Cr3+ complexed with olefin where the Cr3+(cus) was initially five-coordinate. Adsorption at Cr +D- with accompanying displacement of seems less likely. It is difficult to evaluate this possibility. We have no molecular analogies since tri- and tetracoordinate are almost unknown as ligands in molecular coordination chemistry. There is one compound of Cr(III) whose study could be of interest which involves 82)... 

Charge transfer reactions at ITIES include both ET reactions and ion transfer (IT) reactions. One question that may be addressed by nonlinear optics is the problem of the surface excess concentration during the IT reaction. Preliminary experiments have been reported for the IT reaction of sodium assisted by the crown ether ligand 4-nitro-benzo-15-crown-5 [104]. In the absence of sodium, the adsorption from the organic phase and the reorientation of the neutral crown ether at the interface has been observed. In the presence of the sodium ion, the problem is complicated by the complex formation between the crown ether and sodium. The SH response observed as a function of the applied potential clearly exhibited features related to the different steps in the mechanisms of the assisted ion transfer reaction although a clear relationship is difficult to establish as the ion transfer itself may be convoluted with monolayer rearrangements like reorientation. 

In any case, exceptions to the FIAM have been pointed out [2,11,38,44,74,76,78]. For example, the uptake has been shown to depend on the Cj M or rMI (e.g. in the case of siderophores [11] or hydrophobic complexes [43,50]), rather than on the free c M. Several authors [11,12,15] showed that a scheme taking into account the kinetics of parallel transfer of M from several solution complexes to the internalisation transporter ( ligand exchange ) can lead to exceptions to the FIAM, even if there is no diffusion limitation. Adsorption equilibrium has been assumed in all the models discussed so far in this chapter, and the consideration of adsorption kinetics is kept for Section 4. Within the framework of the usual hypotheses in this Section 3, we would expect that the FIAM is less likely to apply for larger radii and smaller diffusion coefficients (perhaps arising from D due to the labile complexation of M with a large macromolecule or a colloid particle, see Section 3.3). 

The behaviour of natural ligands has been discussed in Section 4.3.3. In addition to the direct effect of complexation that is related to a decrease in the free ion activity, it has been shown that some ligands, in particular the HS, can be sorbed directly to biological surfaces, in the presence or absence of the trace metal [228,229]. This result is likely due to the fact that HS and similar macromolecules contain hydrophobic moieties that facilitate their adsorption to the plasma membrane and cell wall [157,230,231]. Because adsorption is expected to occur primarily with sites that are independent of the transporters,... 

Buffle, J., Mota, A. M. and Simoes Gonsalves, M. L. S. (1987). Adsorption of fulvic-like organic ligands and their Cd and Pb complexes at a mercury electrode, J. Electroanal. Chem., 223, 235-262. 

The retention of hydration sheaths upon adsorption is more consistent with an electrostatic view of adsorption than a chemical one, since by remaining a relatively large distance away from the surface, the metal complexes are less likely to participate in surface-ligand exchange. 

Furthermore, an observed change in the coordination of the carboxylate ligands from benzene tri-carboxylic [57] likely involves a second N02 molecule and leads to the formation of a monodentate nitrate bound to the copper (see reaction (10.2)). This rearrangement may cause the appearance of carboxylic groups on the benzene tricarboxylic linkage and the formation of NO, which is released in each case during N02 adsorption process in dry conditions (see reaction (10.3)). 

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