Metal ions detoxification

Ramsay, L. M., and Gadd, G. M. (1997). Mutants of Saccharomyces cerevisiae defective in vacuolar function confirm a role for the vacuole in toxic metal ion detoxification. FEMS Microbiol. Lett. 152, 293-298. 

With metal ions found in approximately a third of all biomolecules [2] there has been significant interest in understanding the mechanisms and coordination chemistry, associated with the transport and regulation of these metal ions. In addition to the essential roles these metal ions play, an excess as a result of misregulation, frequently is associated with various disease states. Furthermore, some metal ions and particularly heavy metal ions, can be exclusively associated with toxicity. Nature has therefore evolved metalloregulatory proteins for heavy metal ion detoxification, which due to the soft nature of the heavy metal irais, is often dominated by Cys coordination chemistry. 

In a separate study, Igwe and Abia46 determined the equilibrium adsorption isotherms of Cd(II), Pb(II), and Zn(II) ions and detoxification of wastewater using unmodified and ethylenediamine tetraacetic acid (EDTA)-modified maize husks as a biosorbent. This study established that maize husks are excellent adsorbents for the removal of these metal ions, with the amount of metal ions adsorbed increasing as the initial concentrations increased. The study further established that EDTA modification of maize husks enhances the adsorption capacity of maize husks, which is attributed to the chelating ability of EDTA. Therefore, this study demonstrates that maize husks, which are generally considered as biomass waste, may be used as adsorbents for heavy metal removal from wastewater streams from various industries and would therefore find application in various parts of the world where development is closely tied to affordable cost as well as environmental cleanliness.46... 

In a simplified model, the metal ions equilibrate on the outside of the cell with biologically produced and excreted ligands l 2 or ligands on the cell surface L3 these reactions are followed by a slow transport step to the inside of the cell. In the cell, the metal ions may be used in biochemical processes or become trapped in inactive forms as a detoxification mechanism. (After Williams, 1983) (cf. Fig. 4.15a). (From Sigg, 1987)... 

A-Vinylpyrrolidone polymers are of special interest in medicine in the process of detoxification as well as for binding and removal of undesirable metallic ions and known as chelatotherapeutic agents [34]. Free radical copolymers of poly(lV-vinylpyrrolidone) and copolymer of JV-vinylpyrrolidone and vinylacetate, vinylamine, vinylamidosuceinic arid are known to bind Cu2+ and other transition metal ions, and the resultant complexes exhibit interesting physico-chemical properties. 

Removal of metal ions and metal compounds from living systems (detoxification)... 

Non-aqueous synthetic methods have recently been used to assemble mesoporous transition metal oxides and sulfides. This approach may afford greater control over the condensation-polymerization chemistry of precursor species and lead to enhanced surface area materials and well ordered structures [38, 39], For the first time, a rational synthesis of mesostructured metal germanium sulfides from the co-assembly of adamantanoid [Ge4S ()]4 cluster precursors was reported [38], Formamide was used as a solvent to co-assemble surfactant and adamantanoid clusters, while M2+/1+ transition metal ions were used to link the clusters (see Fig. 2.2). This produced exceptionally well-ordered mesostructured metal germanium sulfide materials, which could find application in detoxification of heavy metals, sensing of sulfurous vapors and the formation of semiconductor quantum anti-dot devices. 

The thiocyanate ion, S=C=N , also called the rhodanid ion in the early German literature because of the intense red color of its Fe derivative, is obtained by the fusion of alkah metal cyanides with sulfur. It is also the product of the detoxification of the cyanide ion in living systems. Most thiocyanate salts are very soluble in both water and liquid ammonia and are usefiil soluble sources of metal ions in liquid ammonia. Thiocyanogen, N C S , is... 

The main inspiration for the formation of nanoparticles from single amino acids arose from the fact that in nature, many particles are formed from short chain peptides that contain a cysteine or histidine amino acid. These short chain peptides are principally used as a form of detoxification from the effects of high heavy metal ion concentrations in vivo. From these biological examples, the chemistry of these peptides has been expanded to form novel zero-valent and semiconductor nanoparticles under in vitro conditions (Figure 2). 

The story of MRI CAs began with X-ray CAs. DTPA (diethyltriaminepentaacetic acid) was widely used as a chelate for the detoxification and solubilization of bismuth, which is a metal ion in X-ray CAs [3], DTPA attracted the attention of scientist, who developed Gd-DTPA as the first paramagnetic complex in MRI clinical studies [4], It was initially applied to image the central nervous system (CNS). However, owing to its superior anatomical contrast enhancement, it was later applied to the imaging of cardiovascular and neurovascular systems, and in oncology [5],... 

The metal ions in the cell are used in biochemical processes or become trapped in inactive forms (e.g., as complexes of metallothionein) as a detoxification mechanism. Toxic effects are observed in algae when the cellular concentration of toxic metal ions reaches some critical level approaching the minimum cellular concentration of essential trace metals. The system becomes overflooded with toxic metal ions that then react with critical enzymes. 

The detoxification of catalysts poisoned by Group V or VI compounds can be accomplished by reactions in which these inhibitors are converted to substances that do not have unshared electron pairs. For instance, bivalent sulfur compounds can be oxidized to sulfones or sulfonic acids by treatment with hypochlorite or hydroperoxides. "2,108 Thiophene, dimethyl sulfide and other sulfur and metal ion poisons as well as phosphorous"" and arsenic compounds " can be removed from platinum by washing the catalyst with acetic acid. This method for the reactivation of the catalyst is simpler than the oxidation techniques. Acidic or basic inhibitors are removed by the addition of an appropriate amount of base or acid, respectively. The effect of a small amount of inhibitor can frequently be overcome by the use of a larger amount of catalyst. 

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