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Metallothioneins bound

Roesijadi, G. 1994. Behavior of metallothionein-bound metals in a natural population of an estuarine mollusc. Mar. Environ. Res. 38 147-168. [Pg.229]

Metallothionein-bound cadmium and ionic cadmium were separated by ion exclusion on a short chromatographic column. Cadmium in the effluent was detected by coupled ICP-MS (Szpunar et al., 1997). The authors constructed an interface between the column and detector that allowed gradients up to 30% methanol to be used in the eluents. The rapid method of analysis was applied to studies on distributions of cadmium species in mussels. [Pg.417]

In affected cells, copper significantly accumulates as metallothionein-bound copper in the cytosol and copper transport to the organelles - as well as copper efflux - is disturbed. As a result, cuproenzymes... [Pg.467]

Figure 9. Hepatic and renal cytosol from a rat administered CdCl, and Na,A uTM, demonstrating the co-elution of metallothionein bound Cd and Au, Peak III. Conditions Sephadex G-75 (2.5 X 60 cm) column eluted with 50mM Tris-HCl/0.I5M... Figure 9. Hepatic and renal cytosol from a rat administered CdCl, and Na,A uTM, demonstrating the co-elution of metallothionein bound Cd and Au, Peak III. Conditions Sephadex G-75 (2.5 X 60 cm) column eluted with 50mM Tris-HCl/0.I5M...
In the liver a substantial amount of copper is metallothionein bound, in contrast to the traces found in kidney tissue. In these experiments a Zn/Cd/Cu ratio of 9/8/3 was observed. [Pg.368]

Gold (Au), when administered to the rat as either NaAuCl4, or sodium aurothiomalate, accumulates in the particulate component of the kidney and in low molecular weight metalloprotein fraction of the cytosol. Induction of metallothionein synthesis by Au not only seems to be less efficient than that in response to mercury (Hg), cadmium (Cd) and bismuth (Bi) (PiOTROWSKi et al. 1979), but also to be determined by changes in copper distribution (Mo-GiLNiCKA and Webb 1981). Pre-treatment with Cd increased the contents of metallothionein-bound Au, Cu and Zn in the hamster kidney (Mogilnicka and Webb 1982). [Pg.613]

Cadmium introduced into the body through inhalation or ingestion is transported by the albumin fraction of the blood plasma to the liver, where it accumulates and is stored principally as a bound form complexed with the protein metallothionein. Metallothionein-bound cadmium is the main form of cadmium subsequently transported to the kidney it is these 2 organs, the liver and kidney, in which the majority of the cadmium body burden accumu-iates. As much as one half of the total body burden of cadmium may be found in the kidneys (Nordberg and Nordberg 1988). [Pg.1029]

Gold(I) thiolates also undergo reactions with disulfides. An example is 2,2-dithio-bis(2-nitrobenzoic acid) (ESSE) used as a kinetic probe of sulfhydryl reactivity in metallothioneins [39-42]. ESSE is readily attacked by metal-bound thiolates. The reaction with the open chain form of AuSTm seems to occur in two stages. The first attack involves the terminal sulfides and the second attack involves the bridging thiolates [19] ... [Pg.290]

In mammals, as in yeast, several different metallothionein isoforms are known, each with a particular tissue distribution (Vasak and Hasler, 2000). Their synthesis is regulated at the level of transcription not only by copper (as well as the other divalent metal ions cadmium, mercury and zinc) but also by hormones, notably steroid hormones, that affect cellular differentiation. Intracellular copper accumulates in metallothionein in copper overload diseases, such as Wilson s disease, forming two distinct molecular forms one with 12 Cu(I) equivalents bound, in which all 20 thiolate ligands of the protein participate in metal binding the other with eight Cu(I)/ metallothionein a molecules, with between 12-14 cysteines involved in Cu(I) coordination (Pountney et ah, 1994). Although the role of specific metallothionein isoforms in zinc homeostasis and apoptosis is established, its primary function in copper metabolism remains enigmatic (Vasak and Hasler, 2000). [Pg.329]

Cadmium is nutritionally non-essential, toxic and a ubiquitous environmental pollutant. It is found in leafy vegetables, grains and cereals, and since it is present in substantial amounts in tobacco leaves, cigarette smokers on a packet a day can easily double their cadmium intake. It has a long biological half-life (17-30 years in man), accumulates in liver and kidneys and its toxicity involves principally kidney and bone (Goyer, 1997).While Cd interferes primarily with calcium, it also interacts with zinc and can induce the synthesis of metallothionein. Cadmium bound to metallothionein in liver or kidney is thought to be non-toxic, but cadmium in plasma... [Pg.343]

Metallothioneins (MT) are unique 7-kDa proteins containing 20 cysteine molecules bounded to seven zinc atoms, which form two clusters with bridging or terminal cysteine thiolates. A main function of MT is to serve as a source for the distribution of zinc in cells, and this function is connected with the MT redox activity, which is responsible for the regulation of binding and release of zinc. It has been shown that the release of zinc is stimulated by MT oxidation in the reaction with glutathione disulfide or other biological disulfides [334]. MT redox properties led to a suggestion that MT may possesses antioxidant activity. The mechanism of MT antioxidant activity is of a special interest in connection with the possible antioxidant effects of zinc. (Zinc can be substituted in MT by some other metals such as copper or cadmium, but Ca MT and Cu MT exhibit manly prooxidant activity.)... [Pg.891]

The lethal effects of cadmium are thought to be caused by free cadmium ions, that is, cadmium not bound to metallothioneins or other proteins. Free cadmium ions may inactivate various metal-dependent enzymes however, cadmium not bound to metallothionein may have the capacity to directly damage renal tubular membranes during uptake (USPHS 1993). [Pg.52]

Most terrestrial invertebrates have limited access to water and feed on solid matter. As a consequence, they take up most of their nutrients by ingestion of foodstuffs that are also the vehicle for ingestion of contaminants. Many of the class a , metals that are taken up are found in membrane-bound granules in the cells of the hepatopancreas, although uncertainties remain as to the initiation of granule formation. Other metals, such as the class b metal cadmium, may be in the granule or may be bound to a metallothionein type protein. [Pg.388]

A large proportion of the mercury in the kidney is bound to metallothionein, which has a capacity to bind mercury strongly [37-39]. The role for metallothionein in the kidney is probably protective [37]. Chronic dosing of rats with mercuric chloride over a period of 3 weeks induced an approximately 6-fold increase in the renal metallothionein levels, which provides an explanation for the almost linear increase of mercury in kidneys over several weeks of daily exposure. A protective role of metallothionein would explain findings that the... [Pg.192]


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