Metal-binding components

Within a relatively short period the purification of these metal-binding components had been completed by several groups (Grill et al., 1985 Steffens et al., 1986 Reese Wagner, 1987 Jackson et al., 1987). Unfortunately, this led to a series of different names for the same molecules (see Steffens, 1990) for clarity in this chapter, we are using the term phytochelatin as a contrast to gene-encoded MTs. 

It is difficult to interpret many of the data on metal-binding components of plants because these have been determined from experiments on Cd-resistant, Cd-grown cell cultures. This presents two problems. First, plant cell cultures do not necessarily respond physiologically in the same way as intact plants, and secondly, Cd is not an essential metal and hence may not elicit the same responses as an essential one. Our studies thus aimed to examine whole plants, in particular roots, since this is the normal route of metal entry into the plant, and to compare essential with non-essential metal responses. 

What is clear from the analysis of metal-binding components in M. guttatus roots is ... 

Ramamoorthy, S. and Kushner, D.J. (1975) Heavy metal binding components of river water./. Fish. Res. Board Can., 32, 1755-1766. 

It is well known that the trace metal content of a sediment is often to a large extent a function of its chemical and mineralogical characteristics. It is, therefore, very important to use a reliable normalising technique for reporting trace metal concentrations. The key sediment characteristic is surface area or particle size since many of the trace metal binding components (e.g. organic matter, Fe and Mn oxides and hydroxides) are very well correlated with both characteristics. 

A cartoon of a fluorescent switch , turned on or off (quenched) depending on the absence or presence of a metal ion. The ionophore (the cyclic polyether) is the metal-binding component, the fluorophore (the fused-ring aromatic unit) is the component activated by light. Complexation stops electron transfer that otherwise quenches fluorescence. 

In research conducted by Sabbioni and Girardi, NAA was developed for the simultaneous analysis of heavy metals in microsamples of potential metal binding components such as metalloenzymes (calf intestine alkaline phosphatase, cow milk xanthine oxidase, calf thymus deoxynucleotidyltransferase) and nucleic acid (calf thymus DNA), purified by size-exclusion chromatography and ion-exchange chromatography. 

Dexrazoxane (Zinecard) [Chelating Agent] Uses Prevent anthracycline-induced (eg, doxorubicin) cardiomyopathy Action Chelates heavy metals binds intracellular iron prevents anthracycline-induced free radicals Dose 10 1 ratio dexrazoxane doxorubicin 30 min prior to each dose, 5 1 ratio w/ CrCl <40 mL/min Caution [C, ] Contra Component sensitivity Disp Inj SE -1-BM (esp leukopenia), fever, Infxn, stomatitis, alopecia, NA /D Interactions t Length of muscle relaxation Wf succinylcholine EMS Given concurrent w/a chemo agent for treating CA to prevent cardiotox monitor for Infxn and reduced cardiac Fxn use caution w/ succinylcholine, reduced doses may be needed OD May cause extreme BM suppression symptomatic and supportive... 

Fig. 41. Berg s proposed structure of a zinc finger peptide (left) hydrogen bond pattern (center) ribbon diagram illustrating secondary-structure components (right) molecular model illustrating conserved metal-binding and hydrophobic residues. [Reprinted with permission from Berg, J. M. (1988) Proc. Natl. Acad. Set. U.S.A. 85, 99-102.]...

One of the substrates that deserves special attention in our discussion is silicon (Si), and in particular Si wafers for producing solar cells. A variety of sirrface treatments are applied to Si in the solar cell industry Native Si vs. chemically protected (SiN, for example), pohshed versus unpohshed versus patterned to give surface texture, etc. In order to ensirre proper Si-metal contacts, careful control of the conductive ink composition is required. In addition, very high curing temperatures are usually employed in the manufacture of solar cells, thus there is a need for a suitable binding component. Special care is taken to avoid excessive diffusion of metal into the emitter layer, nevertheless, somewhat limited diffusion is desirable so that contact resistance is adequate. ... 

Modified wood with introduced ionizative side chains should be able to bind to various metals, since it is expected that the side chains such as carboxy-methyl and succinyl groups bind easily to produce metal salts. Bonding of metals with wood is an interesting subject from practical or fundamental viewpoints. The properties, especially mobility of wood component molecules, are considered to depend on bonding formation between the side chains and metals. Binding of metals and the confirmation for carboxymethylated and succinylated wood will be mentioned in the following discussion. 

As mentioned in the previous section, metals bind to the modified wood which has carboxyl groups at the end of the introduced side chains because their groups ionize in an aqueous solution. Thus, metals bound to more than two side chains produce crosslinkings, so that the mobility of wood components should be influenced by the bonding. The flexibility is considered to depend on the nature of the metal as well as the amount. The interaction between metals and the modified wood will be examined and the relation between factors related to the flexibility will be discussed on the basis of the interaction. 

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