Detoxification, of metals

Intracellular distribution of essential transition metals is mediated by specific metallochaperones and transporters localized in endomembranes. In other words, the major processes involved in hyperaccumulation of trace metals from the contaminated medium to the shoots by hyperaccumulators as proposed by Yang et al. (2005) include bioactivation of metals in the rhizosphere through root-microbial interaction enhanced uptake by metal transporters in the plasma membranes detoxification of metals by distributing metals to the apoplasts such as binding to cell walls and chelation of metals in the cytoplasm with various ligands (such as PCs, metallothioneins, metal-binding proteins) and sequestration of metals into the vacuole by tonoplast-located transporters. 

The photocatalytic reduction of various metal salts has been a primary route for the preparation of metallized semiconductors, as well as in the detoxification of metal-contaminated waste streams [175], but the details of such reactions are beyond the scope of this article. 

Gharieb, M. M., and Gadd, G. M. (2004). Role of glutathione in detoxification of metal(loid)s by Saccharomyces cerevisiae. Biometals YI, 183-188. 

Lloyd JR and Lovley DR (2001) Microbial detoxification of metals and radionuclides. Curr Opin Biotechnol 12 248-253. 

Volesky, B. 2001. Detoxification of metal-bearing effluents Biosorption for the next century. Hydrometallurgy 59 203-216. 

In accordance with paragraph 66(f) of Part IV(A) of the Verification Annex, the inspection team shall have the right to verify through physical presence and monitoring with on-site instruments the mutilation of metal parts of chemical weapons after destruction of toxic chemical fill and detoxification of metal bodies. The agreed procedures for confirmation of the destruction of metal parts are contained in Attachment 24 to this Agreement. 

Metallothioneins are a group of non-enzymatic, low-molecular mass (6-7 kDa) metal-binding proteins. They play an important role in the detoxification of a number (Zn, Cu, Cd, and Hg) of trace metals (Chassaigne and Lobinski 1998). 

Biosorption strategies consist of a group of applications involving the detoxification of hazardous substances such as heavy metals instead of transferring them from one medium to another by means of biosorbents, which may be either microbes or plants. Biosorption options are generally characterized as being less disruptive and may henceforth be carried out on-site, thereby eliminating the need to transport the toxic materials to treatment sites.12 Biosorption is a very cost-effective method... 

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... 

For detoxification of carbon tetrachloride (CCI4), e.g. in groundwater, de-chlorination is necessary. Iron metal, Fe", is commonly used for this purpose. 

Metallothioneins are an ubiquitous class of proteins with which the important roles of metal storage (Cu, Zn) and detoxification (Cd, Pb, Hg) are associated EXAFS studies have been carried out on a variety of metallothioneins including Zttj, ZUjCuj, ZiigCuj, Cd, and to show that metal atoms are exclusively... 

The MT biomarkers in flounder liver correlate with gradient of contamination in both sediment and fish (Fig. 3, Fig. 4). This may be an indicator of specific stress by organotins, although the expected correlation was not found for metals such as Zn and Cd. Surprisingly, there was a good correlation between the concentration of MT and chemical exposure to total organotin in sediment (r =0.7304). In a few studies it has been shown that, in fish, detoxification of TBT is induced by metalloproteins (Kawano et al., 1996 Padros et al., 2000). 

Macaskie, L. E. Dean, A. C. R. (1989). Microbial metabolism, desolubilization, and deposition of heavy metals metal uptake by immobilized cells and application to the detoxification of liquid wastes. In Biological Waste Treatment, ed. A. Mizrahi, pp. 160-201. New York Alan R. Liss. 

Whitlock, J.L. (1990). Biological detoxification of precious metal processing wastewaters. Geomicrobiology Journal, 8, 241-9-... 

Williams, J. W. and S. Silver. 1984. Bacterial resistance and detoxification of heavy metals. Enzyme Microb. Technol. 6 530-537. 

The mechanism resembles that proposed for a phosphotriesterase (Fig. 12-24). The triesterase catalyzes detoxification of organophosphorus toxins such as parathion (Box 12-E) and seems to have evolved rapidly from a homologous protein of unknown function.721 The phosphotriesterase contains two Zn2+ ions in a dimetal center. An unusual structural feature is a carbamate group, formed from Lys 169 and C02, which provides a bridging ligand for the metal pair.721-725 A carbamylated lysine also functions in ribulose bisphos-phate carboxylase (Fig. 13-11). 

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