Copper-sensitive membrane

A series of at least six genes, in which mutations cause increased sensitivity to copper, were identified in E. co// (Rough 1986) and preliminarily characterized (Brown et al. 1992, 1994). Of these only one, cutE, has been sequenced (Rogers et al. 1991). Two preliminary hypotheses for the function of CutE are a role in intracellular Cu " sequestration and movement (Rogers et al. 1991) and a role in bacterial outer membrane function (Gupta et al. 1993). Whether subsequently identified genes affecting copper sensitivity levels in E. coli will be found to determine P-type ATPases remains to be established. 

A.K. Jain, R.P. Singh, and C. Bala, Solid membranes of copper hexacyanoferrate(III) as thallium(I)-sensitive electrode. Anal. Lett. 15, 1557-1563 (1982). 

Satake et al. reported the use of a coated wire electrode sensitive to procaine and other local anesthetic cations, and their application to potentiometric determination [73]. Electrodes were constructed from a copper wire (0.8 mm diameter), coated with a PVC membrane comprising a mixture of the drug-tetraphenylborate ion-pair, dioctyl phthalate, polyvinyl chloride, and tetrahydrofuran. Potential measurement was made with respect to a Ag-AgCl reference electrode. The electrodes showed linear responses with a Nemstian slope for procaine over the concentration range investigated. The method was used for analyses of the drug in pharmaceutical preparations. 

The high sensitivity of ETA—AAS for Cu has stimulated the development of methods to measure concentrations of the Cu carrier species in biological fluids. Delves [7] analysed the Cu content of the protein fractions separated from 2 pi volumes of serum by cellulose acetate membrane (CAM) electrophoresis. The separated protein bands were cut from the CAM and placed directly into the ETA via a 6 mm x 1 mm hole cut in the wall of the graphite tube. Calibration was achieved by adding 2 pi volumes of aqueous standards to 8 mm x 6 mm strips of CAM. Background correction was essential. Approximately 94% of the Cu was located in the a2 band, where carulo-plasmin would run, whereas other fractions contained less than 5% of the total serum Cu. The recovery of Cu after electrophoresis was quantitative, 99%, and the RSD was 0.086 at 1.74 ng Cu. This method was applied to studies of Cu changes in patients with Menkes Syndrome receiving intramuscular injections of copper as the EDTA complex, and in children with acute lymphoblastic leukaemia. 

DOT CLASSIFICATION 4.3 Label Danger When Wet, Corrosive, Flammable Liquid SAFETY PROFILE Moderately toxic by inhaladon. Corrosive. A severe irritant to skin, eyes, and mucous membranes. Ignites spontaneously in ait. A very dangerous fire hazard when exposed to heat or flame. Forms impact-sensitive explosive mixtures with potassium permanganate, lead(II) oxide, lead(TV) oxide, copper oxide, silver oxide. To fight fire, use water, foam, CO2, mist. When heated to decomposition it emits toxic fumes of CL. See also CHLOROSILANE. 

It is known that the method used to truncate the interatomic interactions can have an important effect. It has been demonstrated that the dielectric properties of simulated water are a sensitive function of the extent to which the long-range electrostatic interactions are included [40]. Simulations of phospholipid membrane-water systems showed that the behavior of the water near the membrane is incorrectly described if the electrostatic interactions are truncated at too short a distance, and hot water/cold-protein behavior is observed [10]. Given the importance of the potential/force truncation, we have investigated this issue for the copper system being simulated. This has been done in terms of the same properties as were used in examining convergence. 

Skin sensitization is believed to occur as a result of nickel binding to proteins (particularly on the cell surface) and hapten formation. Essentially, the body perceives the nickel-protein complex as foreign and mounts an immune reaction to it. For example, sweat may react with the nickel in plated jewelry that comes in direct contact with skin dissolved metal may penetrate and react with proteins in the skin and lead to immune sensitization. Nickel may substitute for certain other metals (especially zinc) in metal-dependent enzymes, leading to altered protein function. High nickel content in serum and tissue may interfere with both copper and zinc metabolism. It also readily crosses the cell membrane via calcium channels and competes with calcium for specific receptors. 

Direct, nonenzymatic reduction of metal complexes by the cell wall or cell membrane of T. weissflogii is evidenced in two ways. First, a nonlinear rate of Cu(BPDS)2 reduction occurs initially after addition of the substrate. Second, this reductive capacity of the cells is sensitive to pretreatment with an oxidant such as Cu(II) (Fig. 3b). These observations demonstrate that the reducing sites are irreversibly consumed and are not replaced or regenerated quickly. The copper pretreatment does not interfere with the cell s ability to reduce metal complexes through an enzymatic pathway. 

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