Protein metals/metalloids

It is well known that a great variety of biomolecules exist where metals and metalloids are bound to proteins and peptides, coordinated by nucleic acids or complexed by polysaccharides and small organic ligands such as organic acids.55 Most proteins contain amino acids with covalently bonded heteroelements such as sulphur, selenium, phosphorus or iodine.51 Several reviews have been published on the development of mass spectrometric techniques for bioanalysis in metal-lomics , which integrate work on metalloproteins, metalloenzymes and other metal containing biomolecules.1 51 53 54 56-59 The authors consider trace metals, metalloids, P and S (so-called... 

Table 16.5. Reduction of metals and metalloids by proteins from anaerobic bacteria.

In biological systems metals and metalloids not only interact with high molecular mass constituents, for example proteins and DNA, but also with a host of low molecular mass ligands, amino acids, peptides, inorganic ligands and others. The above discussion also apply to these species. A fraction of some elements are unbound and these could be treated as hydrated free ions. 

Analysis of Phosphorus, Metals and Metalloids Bonded to Proteins... 

Bioavailable metals and metalloid species are either adsorbed or incorporated into the structure of proteins, lipids, nucleic acids, amino acids, sugars, vitamins and hormones to form complexes of varying degrees of thermodynamic stability and reactivity. These complexes could be classified as either metal-proteins or metalloproteins on the basis of their stability during isolation and purification (Vallee and Coleman, 1964). Whereas metal-proteins are relatively labile and the metal is easily lost during dialysis, metalloproteins are stable and inert. 

In general, species containing transition metals and metalloids such as As, Sb, Se and Sn are thermodynamically more stable than those of the alkali and alkaline earth metals. Transition metals and metalloids form an integral part and are linked to the organic constituents by covalent bonds. In contrast alkali and alkaline earth metals are attached loosely by predominantly ionic bonds. Readers interested in the fundamentals of metal-protein interactions are referred to books... 

Metalloids, such as As and Se, are known to be metabolized by living organisms in a way that leads to the formation of a covalent bond between the heteroatom and the C atom incorporated in a larger structure (e.g., arsenosugars, Se-containing amino acids, peptides, and proteins). The complexation of metals by components of food leads to a number of relatively poorly characterized metal... 

It is well known that a large number of chemical substances, including toxic metals and metalloids such as arsenic, cadmium, lead, and mercury, cause cell injury in the kidney. With metal-induced neurotoxicity, factors such as metal-binding proteins, inclusion bodies, and cell-specific receptor-like proteins seem to influence renal injury in animals and humans. It is of interest to note that certain renal cell populations become the targets for metal toxicity, while others do not. In fact, the target cell populations handle the organic and common inorganic nephrotoxicants differently. ... 

S-oxidizing bacteria), many are probably most appropriate for ex situ use in bioreactors, where the mobilized or immobilized metal can be separated from soil components (White et al., 1998). Living or dead fungal and bacterial biomass and metabolites have been used to remove metals, radionuclides, and metalloids from solution by biosorption or chelation (Macaskie, 1991 Gadd, 2001). The metalloregulatory protein MerR, which exhibits high affinity and selectivity toward mercury, was exploited for the construction of microbial biosorbents specific for mercury removal (Bae et ah, 2001, 2002, 2003). Whole-cell sorbents... 

Metallomics is the study of metallomes, interactions and functional connections of metal ions and their species with genes, proteins, metabolites, and other biomolecules within organisms and ecosystems, where a metallome is the entirety of metal and metalloid species present in a cell, cell compartment, tissue or organism, defined according to their identity, quantity, and localization. ... 

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