Macromolecular ligands

Water-soluble hydrogenation catalysts with macromolecular ligands... 

Finally, continuous exposure of certain receptors to their macromolecular ligands can lead to rapid downregulation of cell surface receptors, especially if receptor recycling within the cells is incomplete. Fortunately, expression of many receptors, for example for certain cytokines, growth hormones and adhesion factors, can be extensively upregulated in the disease process and this can result in disease-induced drug-targeting. 

Macromolecular ligands (e.g., proteins) [224], polysaccharides [225], small ligands (e.g., triazine dyes) [226], metal chelates [227], and inhibitors [228] can provide unparalleled selectivity in forming Hgand-Hgate affinity complexes. 

Simionescu and coworkers (36) also carried out for the first time mechanical reactions leading to complex metal chelates with macromolecular ligands. Fragments formed from the mechanical condensation of polyethylene tereph-thalate with ethylene diamine serve as ligands for ferric chloride. The reaction was performed in a vibromill (amplitude 4 mm, 1475 rpm at 18° C). 

Kuntz ID, Blaney JM, Oatley SJ, Langridge R, Ferrin . A geometric approach to macromolecular-ligand interactions. JMol Biol 1982 161 269-288. 

In a novel procedure, chemical modification of uncrosslinked atactic polystyrene by acetylation followed by a Claisen condensation with ethyl perfluoro-propanoate has been used to prepare a macromolecular ligand bearing phenyl,... 

Li, D., et al., The inter-ligand Overhauser effect a powerful new NMR approach for mapping structural relationships of macromolecular ligands. J Biomol NMR, 1999, 15, 71-76. 

The present paper has demonstrated the versatility of the dialysis technique in studies of interactions between metal ions and humic acid samples. The method allows facile determination of interaction constants, as well as of complexing capacities of the humic acid samples. It is noteworthy that the method described here, without modifications, can be applied to other areas of complex chemistry involving macromolecular ligands. 

However, in contrast to LMWM, the quantitative parameters of chelation involving macromolecular ligands have not been studied well enough. This is associated with a need to consider a number of additional factors controlled by the chain type of the ligand. It is apparent that for PCMU the following three levels of their spatial arrangement should be considered ... 

A clearly defined ability of porphyrins and phthalocyanines to be additionally coordinated (extracoordinated) with a planar complex of ligands occupying the 5 and 6 positions in the inner coordination sphere is completely utilized during their interaction with polymeric carriers. A survey of the macromolecular ligands used for this purpose is made elsewhere [7b, e]. 

Of some interest are chelation processes occuring along with the synthesis of macromolecular ligands. This can be exemplified by a mechano-chemical activation of polyethylene terephthalate and en polycondensation to give the following complexes [112] ... 

Polynuclear PCMU can be synthesized by means of all the above described methods for the preparation of mononuclear PCMU, such as binding a few metals with polynucleating macromolecular ligands, immobilization of the ready-made and well characterized polynuclear complexes or clusters on polymers and assemblage of polymetallic sites on polymer supports. 

In principle, affinity electrophoresis is carried out in polyacrylamide gels. The receptor protein moves to a given position relative to a tracking dye or other protein. Addition of the macromolecular ligand in various concentrations in the gel retards the movement of the receptor protein. If in addition, a small haptenic molecular oligosaccharide is added to the gel, the mobility is restored. From either set of measurements the of the receptor-macromolecular ligand or receptor-hapten interaction can be calculated. 

This paper summarises the results of the preparation and investigation of nickel, zirconium and titanium complexes immobilized in rubber base with grafted macromolecular ligands [6-10]. 

In Cu compounds of high covalence no precise decision can be reached regarding the oxidation state of the copper (53), while in ionic systems reference to the occupancy of the 3d subshell is sufficient. Thus, the oxidation states given in I—IY are of merely formal nature. The interesting phenomenon in this scheme is the redox mesomerism of Cu which implies that the chelated metal ion could have different biochemical actions. Type I would represent the reversible oxygenation as found in haemo-cyanin, type II would be the superoxide dismutation, provided OI-really is the substrate, and types III and IV are represented by the catalatic and oxidative action displayed by a considerable number of copper proteins (polyphenol oxidases, amine oxidases etc.). The biochemical specificity of each chelated copper is more of less given by the macromolecular ligands. 

Giroux EL and Henkin RI (1973) Macromolecular ligands of exchangeable copper zinc and cadmium in human serum. Bioinorg Chem 2 125-133. 

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