Phosphate transport system, arsenate

Figure 1 Bacterial reduction of arsenate and oxidation of arsenite. (A). Cytoplasmic arsenate reductase (ArsC) as encoded by bacterial ars operons along with chromosomaUy encoded Pit and Pst phosphate transport systems with arsenate as an alternative substrate. After reduction from arsenate to arsenite, arsenite is removed from the cell by the ArsB membrane protein. (B). Anaerobic periplasmic arsenate reductase. (C). Aerobic periplas-mic arsenite oxidase, hnked via azurin to the respiratory chain.

Cells accumulate arsenic using an active transport system normally used in phosphate transport. 

Identification of the specific species of the adsorbed oxyanion as well as mode of bonding to the oxide surface is often possible using a combination of Fourier Transform Infrared (FTIR) spectroscopy, electrophoretic mobility (EM) and sorption-proton balance data. This information is required for selection of realistic surface species when using surface complexation models and prediction of oxyanion transport. Earlier, limited IR research on surface speciation was conducted under dry conditions, thus results may not correspond to those for natural systems where surface species may be hydrated. In this study we review adsorbed phosphate, carbonate, borate, selenate, selenite, and molybdate species on aluminum and iron oxides using FTIR spectroscopy in both Attenuated Total Reflectance (ATR) and Diffuse Reflectance Infrared Fourier Transform (DRIFT) modes. We present new FTIR, EM, and titration information on adsorbed arsenate and arsenite. Using these techniques we... 

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