Polyvalent inhibition

FIGURE 5.24 Sialic acid conjugated dendritic polyglycerol nanoparticles with diameters in the range of 60 nm efficiently block viral infections by polyvalent inhibition of the hemagglutinin in contrast to their smaller multivalent analog. Source Quadir and Haag [54]. Reproduced with permission from Elsevier. 

Ghelants and Precipitation Inhibitors vs Dispersants. Dispersants can inhibit crystal growth, but chelants, such as ethylenediaminetetraacetic acid [60-00-4] (EDTA), and pure precipitation inhibitors such as nitrilotris(methylene)tris-phosphonic acid [6419-19-8], commonly known as amino trismethylene phosphonic acid (ATMP), can be more effective under certain circumstances. Chelants can prevent scale by forming stoichiometric ring stmctures with polyvalent cations (such as calcium) to prevent interaction with anions (such as carbonate). Chelants interact... 

G. Thoma, M. B. Streiff, A. G. Katopodis, R. O. Duthaler, N. H. Voelcker, C. Ehrhardt, and C. Masson, Non-covalent polyvalent ligands by self-assembly of small glycodendrimers A novel concept for the inhibition of polyvalent carbohydrate-protein interactions in vitro and in vivo, Chem. Eur. J., 12 (2006) 99-117. 

The biological activity of flavonoids has attracted much interest in the part twenty years and a few compounds of this class have been shown to have AChEI effects. The flavanone naringenin (74) from Citrus junos (Rutaceae) ameliorated scopolamine-induced amnesia in mice, which may be related to an antiAChE effect, since naringenin was shown to inhibit AChE in vitro dose dependently. A recent theoretical study has shown that flavonoids and xanthones exhibit polyvalent effects such as antioxidant, amyloid reduction and cholinesterase inhibition, which made them interesting candidates for further studies. 

This first enzyme, whose activity is modulated by an end-product, is an allosteric enzyme where, in addition to the active site, it has another space specific for binding the ligand which modulates the active site. Some negative modulators inhibit, as shown above with isoleucine on threonine hydratase, while others may stimulate or positively modulate the enzyme. Some enzymes have only one modulator and are called monovalent, while others have have several and are called polyvalent modulators. Moreover, some allosteric enzymes have both negative and positive modulators. Figure S.33 illustrates some patterns of allosteric modulation. The advantage of these control systems is that cellular materials are economically used. 

System 2. The presence of polyvalent lattice ions in the system containing minerals with PDIH+ and OH- leads to their specific adsorption in the EDL and is often accompanied with a change in IP and PZC provided the surface charge has the opposite sign of that of the adsorbing lattice ion. This leads to an inhibition or activation of the mineral surface as shown in Fig. 16179). The same is true for a hydrolytic product of lattice ions exhibiting a stronger surface activity than non-hydrolyzed ions, as a result of a combined electrostatic and chemisorptive effect. 

Care must be taken that finish systems not contain de-foamers or foam destabilizers. Polyvalent metal salts are often used as catalysts in resin systems and several of these, such as zinc nitrate,strongly inhibit foam generation. This is not dissimilar to the foam inhibiting action of hard water on fatty acid soaps. 

The results of an in vitro study on immortalized mouse distal convoluted tubule cells have suggested that aminoglycosides act through an extracellular polyvalent cation-sensing receptor and that they inhibit hormone-stimulated magnesium absorption in the distal convoluted tubule (80). 

Santoianni and Rothman found DNase II (active at pH 5), but no DNase I in rat and human epidermis (S3). It was not present in the dermis. Magnesium ions at concentrations above 1 milf and polyvalent anions above 5 milf inhibited the activity. The activity found in human epidermis was 7.6 /ig of deoxypentose-P liberated per hour per milligram of supernatant protein (or 0.4 ng of deoxypentose-P per hour per milligram of dry tissue or 0.5 tg of deoxypentose-P per hour per microgram of DNA-P). This is equivalent to approximately 70 ng of DNA split per minute per milligram of dry tissue, or 8 ng of DNA split per minute per microgram of DNA in the tissue. Rat epidermis and rat spleen contained approximately 8 times as much DNase II as human epidermis. 

The compounds of the present study were prepared from the C-allyl sialic acid derivative described by Paulsen et al.102 and Vasella, et al.103 The ethyl ester of this compound was converted to the amide, shown. Completion of the synthesis involved reductive animation to the illustrated glucose based polymer thus giving the product. In one particular instance, the starting materials were combined to yield a product containing approximately 30% of the sialic acid analog. This polyvalent C-sialoside inhibited infection by influenza virus with an IC50 of 0.2 M. 

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