The biochemical basis for resistance to metal ion toxicity is emerging though it is complicated by the different resistance mechanisms. Several strategies for resistance to toxic metal ions have been identified:
The development of energy driven efflux pumps which keep toxic element levels low in the interior of the cell. Such mechanisms have been described for Cd(II) and As(V).
Oxidation (e.g. AsO2‐ to AsO43‐) or reduction (e.g. Hg2+ to Hg0) can enzymatically and intracellularly convert a more toxic form of an element to a less toxic form.
The biosynthesis of intracellular polymers which serve as traps for the removal of metal ions from solution such as traps have been described for cadmium, calcium, nickel and copper.
The binding of metal ions to cell surfaces.
The precipitation of insoluble metal complexes (e.g. metal sulfides and metal oxides) at cell surfaces.
Biomethylation and transport through cell‐membranes by diffusion controlled processes.
In this short review I shall discuss the implications of biomethylation as a detoxification mechanism for microorganisms as well as for certain higher organisms. 相似文献
Previous studies have demonstrated that cadmium can induce biochemical and physiological changes in yeast Saccharomyces cerevisiae. However, studies on the influence of cadmium on the ion balance in the cell and the interaction between cadmium and other ions are still relatively few in number. By using inductively coupled plasma-atomic emission spectrometry, the contents of some cations, including Zn2+, Ca2+, Fe3+, Cu2+, Mg2+, K+, and Na+ were measured. The data showed that the levels of Zn2+ and Fe3+ were increased, while those of Cu2+, K+, and Na+ were decreased after cadmium treatment. Afterwards, using the drop test assay, the interactions between cadmium and the selected ions were investigated. The results suggested that the cytotoxicity of cadmium could be attributable to the interference of cadmium with the intracellular cation homoeostasis. Calcium channel transporter Cch1 participates in the intracellular uptake of cadmium. Additionally, Zn2+, Ca2+, Fe3+, Mg2+, and K+ can rescue the toxic effect of cadmium in yeast. 相似文献