Binding heavy metals

Finally, micellar systems are useful in separation methods. Micelles may bind heavy-metal ions, or, through solubilization, organic impurities. Ultrafiltration, chromatography, or solvent extraction may then be used to separate out such contaminants [220-222]. 

MIR), requires the introduction of new x-ray scatterers into the unit cell of the crystal. These additions should be heavy atoms (so that they make a significant contribution to the diffraction pattern) there should not be too many of them (so that their positions can be located) and they should not change the structure of the molecule or of the crystal cell—in other words, the crystals should be isomorphous. In practice, isomorphous replacement is usually done by diffusing different heavy-metal complexes into the channels of preformed protein crystals. With luck the protein molecules expose side chains in these solvent channels, such as SH groups, that are able to bind heavy metals. It is also possible to replace endogenous light metals in metal-loproteins with heavier ones, e.g., zinc by mercury or calcium by samarium. 

RAFT polymerization lends itself to the synthesis of polymers with thiol end groups. Several groups have utilized the property of thiols and dilhioesLers to bind heavy metals such as gold or cadmium in preparing brushes based on gold film or nanoparticles1 8 761 763 and cadmium selenide nanoparticles.763 76 1... 

Gekeler, W., Grill, E., Winnacker, E.-L. Zenk, M.H. (1989). Survey of the plant kingdom for the ability to bind heavy metals through PCs. Zeitschrift fur Naturforschung 44c, 361-9. 

Figure 2.14. Schematic drawing of functionalized monolayers on ordered mesoporous supports. One end group of the monolayers is covalently bonded to the silica surface and the other end group can be used to bind heavy metals or other functional molecules. Reproduced with permission from [99],...

The ability of cyclam derivatives to bind heavy metal ions [131] has been exploited with (60) [75] which shows good fluorescence enhancements with zinc and cadmium ions at pH 10. In such polyamine receptors, it is necessary that all the nitrogen lone pairs occupy the first coordination sphere of the metal ion in order that the fluorescence is efficiently revived. The unusual spectral shape of... 

Peptides and proteins could be efficient metal binding ligands, because they have the functional groups for metal binding in their amino acid residues, and they can be produced at low cost by recombinant technologies. While many peptides and proteins are known to work as metal transport proteins in biological systems, metallothioneins (cysteine rich proteins with molecular weight of ca. 7 kDa) have attracted researchers attention for decades because they bind heavy metals in vivo [2]. The metallothioneins are considered to be involved in detoxication and metabolism of heavy metals. 

Phospholipids increase the oxidative stability of fats and oils and fatty foods, in that they act as synergists of tocopherols (Khan and Shahidi, 2001) and other natural phenolic antioxidants, such as flavonoids. They stabilize even polyunsaturated edible oils (Kourimska et al., 1994) and fish oils. Phosphatidylcholine reacts with peroxy radicals to yield trimethylammonium oxides. Phosphatidylamines react with hpid hydroperoxides in the non-radical way to form imines. Phospholipids can also bind heavy metals, which act as prooxidants, to produce inactive, undissociated salts. 

Ethylenediamintetraacetic acid EDTA 2mM Bind heavy metals, avoid poisoning of sensitive proteins, deactivate metalloproteases, reduce sulfhydryl oxidation... 

Nalidixic acid 4.33) binds heavy metals between the carboxylic- and the oxo-groups (Crumplin, Midgley and Smith, 1980). It is not known if this plays a part in its biological action, which is inhibition of the synthesis of DNA (Section 4.0.5, p. 136). The antibacterial action of kojic acid (77./7), a pyrone extracted from certain fungi, is enhanced by metallic cations (Weinberg, 1957). Bacitracin, a polypeptide antibiotic (Section 13.2), loses its antibacterial action against Staph, aureus in the presence of EDTA the action is restored by bivalent cations (Adler and Snoke, 1962). 

Crude bentonite and sodium bentonite (soda activated bentonite) bind heavy metal ions by cation exchange. Usually, the preference is (see also [70])... 

The thiols can act as chelators and bind heavy metal ions through mercaptide formation. The chelation may also involve the amino group. Copper-chelation by penicillamine, changes in copper metabolism and altered concentrations of coppercontaining proteins like ceruloplasmin and altered activity of the copper-dependent superoxide dismutase (an intracellular enzyme for removal of toxic superoxide radicals) may be of importance. Chelation of copper may also increase the prostaglandin E/f ratio, which is assumed to have an anti-inflammatory effect. 

Iota-carrageenans can also strongly bind heavy metal The biosynthesis of a-L-guluronic acid occurs via the cations such as a degradation product of radioactive enzymatic epimerization of (3-D-mannuronic acid (Chapter strontium, and Pb within pH range from 4.0 to 6.0 14), and it is accepted that alginic acids are formed by... 

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