Metal ions cytoplasmic

Glycophorin A is also considered to be involved in the binding of such important biological metal-ions as Ca " and Mg to the red-cell mem-brane. " This phenomenon may be important, because it has now been shown that glycophorin is a crucial component in the cytoplasmic, Ca -induced, morphological changes observed in red blood cells. This may result from the fact that glycophorin interacts with the proteins that create the red-cell, cytoskeleton structure. ... 

This ability to grow in polluted soils and withstand high heavy metal concentrations rests on complex mechanisms involving both avoidance through exclusion of metal ions from the cytoplasm and tolerance of high internal metal concentrations (126), this being often dependent on the induction of specific genes and proteins (126,127). 

In this section we summarise the manner in which i -metals. Fig. 6, and where possible specifically the platinum complexes of concern here, interact with biological molecules. Some radio-tracer studies have been carried out on the distribution of platinum complexes in whole bacteria grown in media inocculated with the metal ion. The results are summarised in Table 11. It is noteworthy that the bacteriocidal complex [PtClg]2- was taken up almost entirely by the cytoplasmic protein whereas the filamentous forming neutral species, [Pt(NHs)2Cl4], was... 

Note The inside here is the cytoplasm which has not changed to a large extent to this day and die number for heavy metal ions are estimates. 

We now look at the values of the free M concentration and hence to the binding strength to selected A synthesised in the cell. The constants are closely common to all cells in their common compartment, their cytoplasm. The values, suited to metabolism, can be put in series in which Na+ and K+ bind poorly and only to a few of the weakest donors based on neutral O-donor centres while other metal ions bind more strongly to O, N and S donors of proteins or small organic molecules in a well-recognised order, i.e. in the Irving/Williams series (see Section 2.17) ... 

Protection from any poisonous metal ions liberated from their sulfides by oxidation by 02 was secured by the use of strong chelating agents in the cytoplasm, most of which are proteins, or small molecules, thiolates, which were connected to exit pumps or to chemical metabolic tricks for metal ion neutralisation (sequestration). The genes that code for these proteins are usually to be found on plasmids in the cytoplasm of the bacterial cells (Section 5.15). Bacteria adapt very quickly to... 

Protection of the cytoplasm from damaging metal ions, for example, of increasing Zn and Cu, released by oxidation of sulfides, which was managed by internal carrier chelation or chemical modification and transfer to exit pumps. 

Another feature of mitochondria is that they handle the syntheses of both iron/sulfur and iron haem units. It appears as if handling metal ions, including that of iron, is risky in the cytoplasm. In fact, other metal ions are pumped out of cells or into vesicles and in some cases into mitochondria - especially calcium. 

The distribution of elements in single-cell non-photosynthetic eukaryotes is probably best seen in terms of the well-defined compartments of yeast. The central cytoplasmic compartment containing the nucleus has many free element concentrations, only somewhat different from those in all known aerobic prokaryotes (Figure 7.7). (The nuclear membrane is a poor barrier to small molecules and ions and so we include the nucleus with the cytoplasm.) We do not believe in fact that the free cytoplasmic values of Mg2+, Mn2+, Fe2+, Ca2+, and possibly Zn2+, have changed greatly throughout evolution. As stressed already there are limitations since free Mg2+ and Fe2+ are essential for the maintenance of the primary synthetic routes of all cells, and changes in other free metal ions could well have imposed... 

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