Copper, sequestering

Facin6, R.M. Carini, M. Aldini, G. Berti, F. Rossoni, G. Bombardelli, E. Morazzoni, P. Procyanidines from Vitis vinifera seeds protect rabbit heart from ischemia/ reperfusion injury antioxidant intervention and/or iron and copper sequestering ability. Planta Med. 1996, 62, 495-502. 

Textiles. Sorbitol sequesters iron and copper ions in strongly alkaline textile bleaching or scouring solutions (see Textiles). In compositions for conferring permanent wash-and-wear properties on cotton fabrics, sorbitol is a scavenger for unreacted formaldehyde (252) and a plasticizer in sod-resistant and sod-release finishes (253). 

Other heavy metal impurities (especially copper and nickel) have similar adverse effects on all generic alloy types. In their case sequestering has not proved successful and control of input quality is used to keep their concentration acceptably low. ... 

Phosphonates exhibit all the properties of polyphosphates, such as threshold effect, crystal distortion, and sequestration, but are superior in their effectiveness. They provide good chelates for calcium, magnesium, iron, and copper and are commonly used where iron fouling is a problem. Their sequestering properties are generally superior to other common chelants, such as EDTA and NTA. 

NOTE Triethanolamine (TEA) also sequesters iron, is less toxic than ammonia, and reduces the risk of copper cracking. 

In the past, copper was believed to be toxic to most microbiological species. Although this may be true in a test tube under laboratory conditions, it is not generally true in the real world. In this real world, microbial communities excrete slime layers which tend to sequester the copper ions and prevent their contact with the actual microbial cells, Aus preventing the copper from killing the microbes. Many cases of MIC in copper and copper alloys have been documented, especially of heat-exchange tubes, potable water, and fire protection system piping. 

The function of the molecular sieves in this case is believed to be as a base that sequesters the protons, which otherwise would promote a variety of side reactions. With chiral catalysts, the carbonyl ene reaction becomes enantioselective. Among the successful catalysts are diisopropoxyTi(IV)BINOL and copper-BOX complexes. 

The presence of salts and additives can have an important influence on the performance of an FBA. Traces of transition-metal ions such as iron and copper have an adverse effect on fluorescence [30], but this can be controlled using conventional polyphosphate or EDTA-type sequestering agents [31]. Other salts, even sodium sulphate or sodium chloride, have been claimed to enhance the fluorescence of FBAs in solution [32]. Apart from the normal... 

A substance which results in the chemical inactivation of a metal. The catalytic effect of heavy metals, mainly copper and manganese, on the oxidation of unsaturated compounds such as rubber, results in very rapid deterioration. Chelating agents convert the metal into a chelate co-ordination compound and thus render the metal inactive. The term sequestering agents has been applied to chelating agents but this infers that the metal has been removed and not merely inactivated. 

Copper sulfate is used to control protozoan fish ectoparasites including Ichthyopthirius, Tri-chodina, and Costia. The effectiveness of the treatment diminishes with increasing total alkalinity and total hardness of the water (Straus and Tucker 1993). Copper compounds now used to control protozoan parasites of cultured red drum (Sciaenops ocellatus) include copper sulfate, copper sulfate plus citric acid, and chelated copper compounds (forms of copper bound by sequestering agents, such as ethanolamine) chelated copper compounds are considered less toxic to fish than copper sulfate and at least as effective in controlling parasites (Peppard etal. 1991). 

We will discuss in more detail in Chapter 8 how intracellular copper levels are maintained at extremely low levels by a series of copper chaperone proteins, which sequester newly assimilated copper within the cytoplasm of cells and deliver it in a targeted manner to be incorporated into specific copper-containing proteins. While copper uptake across the gastrointestinal tract is poorly understood—most probably utilising the divalent cation transporter... 

Both copper and zinc appear to be stored in many bacteria in cysteine-rich proteins, called metallothioneins, which will be discussed from a structural point of view later in the chapter. The expression of these metal sequestering, low-molecular weight, cysteine-rich proteins, is often induced by both monovalent Cu(I) and divalent Zn(II), as well as by the non-biologically necessary, but potentially toxic, Ag(I) and Cd(II). 

While unicellular fungi do not require metal transport systems, multi-cellular fungi and plants most certainly do, and we consider their transport in plants, and then consider how metal ions are sequestered in storage compartments before addressing their homeostasis. Once again, we consider in turn these processes for iron, copper and zinc. Since iron metabolism has been most intensively studied in S. cerevisiae, of all the fungi, we will focus our attention on iron homeostatic mechanisms, however, as the reader will see shortly, copper and zinc homeostasis have many similarities. 

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