Non-specific interactions

Furthermore, the number of diene - dienoplrile combinations that can be expected to undergo a Lewis-acid catalysed Diels-Alder reaction is limited. Studies by Wijnen leave little doubt that the rate of typical Diels-Alder reactions, where the dienophile is activated by one or more carbonyl functionalities, does not respond to the presence of Lewis acids in aqueous solution , at least not beyond the extent that is expected for non-specific interactions (salt effects). No coordination of the Lewis acid to the dienophile was observed in these cases, which is perhaps not surprising. Water is... 

There are few, if any, specific inhibitors of lipase activity. Instead, reported inhibition of lipase by saponins (Han et al., 2002), polysaccharides and tannins (Longstaff and McNab, 1991) is probably due to the non-specific interactions these phytochemicals have with proteins. 

D protein arrays based on biotin-streptavidin architectures are likely to be the system of choice due to their ease in handling, excellent signal-to-noise ratio and non-specific interactions. 3D surfaces based on porous gold, sol-gel materials, polymer brushes and dextran surfaces are widely used to mimic the properties of bulk solution and increase the immobilization capacity of proteins. 

Roth, J., Taatjes, D.J., and Warhol, M.J. (1989) Prevention of non-specific interactions of gold-labeled reagents on tissue sections. Histochemistry 92, 47-56. 

Lipophilic ion exchangers traditionally used for polymeric membrane preparation are the anionic tetraphenylborate derivatives and the cationic tetraalkylammonium salts. The charges on both lipophilic ions are localized on a single (boron or nitrogen) atom, but the steric inaccessibility of the charged center, due to bulky substituents, may inhibit ion-pair formation in the membrane and provide, when necessary, non-specific interactions between ionic sites and sample ions. 

Whereas lipoplexes/polyplexes generally protect the plasmid from serum nucleases, the overall positive charge characteristic of these structures leads to their non-specific interactions with cells... 

If the assertion that VD is driven by non-specific interactions between drugs and macromolecular structures in tissues, then it logically follows that VD would be correlated to physiochemical parameters. Since such parameters are amenable to computation from structure alone, the prediction of human VD from chemical structure is feasible. Such in silico approaches have only been described over the past few years, as computational chemistry tools have advanced. 

This scheme disregards mass transfer limitations and represents only a simplified model. Formation of A S may involve specific interactions, such as hydrogen bonds, coordination, or ir-complex formation, or non-specific interactions, such as van der Waals or hydrophobic bonds. Non-specific interactions are insignificant for small polar molecules, but may contribute significantly to the surface complex formation if the hydrophobic moiety is large ( 5, 6) ... 

It is important to emphasize that the introduction of a spacer should never affect the binding characteristics of the support. The selected spacer must not introduce any charges and should not be sufficiently hydrophobic to cause any kind of non-specific interaction. Several molecules can fulfill this demand but only a few of them are regularly used. Most of these contain terminal amino or carboxylic groups. In particular these are diaminodipropyl amine, 6-aminocapronic acid, 1,6-diaminohexane, ethylenediamine, l,3-diamino-2-propanol, succinic acid, 1,4-butanediol diglycidyl ether, and others [96]. Extensive description of other bifunctional reagents can be found in the book of Wong [89]. 

Recent attempts to unify the polarity scales of solvents (for non-specific interactions) are of great interest in rationalizing the medium effects166. Generally, the spectroscopic properties of appropriate substances are used to check the solvating ability of solvents. 4-Nitroaniline is a useful indicator for estimating solvent polarity because it is an electron acceptor molecule which presents incomplete complexation with weak donor solvents167. 

It was found that a better representation of non-specific interactions between solvents and the monosubstituted dipolar trimethylammonium ions is gained from the product of tt and the solvent dipole moment (/x). The obtained results were compared with the gas-phase basicity and the solvent attenuation factors (SAF) were calculated". 

Busscher, H. J., and Weerkamp, A. H. (1987). Specific and non-specific interactions in bacterial adhesion to solid substrata. FEMS Microbiol. Rev. 46,165-173. 

Clearly, the mechanistic contributors to the extent of plasma and tissue binding are numerous, and the VD term represents a simplistic picture of potentially hundreds, maybe thousands, of individual tissue binding interactions. Despite this possible complexity, there may be a few individual types of tissue binding that are mostly responsible for tissue partitioning, and as described elsewhere in this chapter, this phenomena may be more related to non-specific interactions that are a function of gross physicochemical properties of the drug than specific binding interactions. 

The affinity between the carbon surface and the fluid phase plays a major role in adsorption processes, as the generally non-specific interaction substantially affects... 

This countercharge can accumulate in the electrolyte side of the interface by coulombic non-specific interactions as well as by specifically adsorbed ions and dipoles and it can extend, to some degree, into the electrolyte, especially at low ionic concentrations. 

Histamine H3 receptor stimulation is not involved in the direct effects of histamine in the permeability response in in vivo rats, (Pile and Smaje., 1992) In this last study, Hi and H2 receptors seem to have a dominant role. However, the H3-receptor antagonist thioperamide prevents the effects induced by histamine and by the Hi-agonist 2-thiazolylethylamine, thus suggesting non-specific interactions of these histamine receptor ligands... 

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