Arsenate reduction biochemistry

This chapter concentrates on arsenate respiration by Chrysiogenes arsenatis and Desulfomicrobium sp. str. Ben-RB. The evidence indicates that they have specific respiratory arsenate reductases involved in energy generation. The isolation, phytogeny, physiology, and biochemistry of arsenate reduction are described separately for each organism. 

Heteropolyacids (HPA) are the unique class of inorganic complexes. They are widely used in different areas of science in biochemistry for the precipitation of albumens and alkaloids, in medicine as anticarcinogenic agents, in industry as catalysts. HPA are well known analytical reagents for determination of phosphoms, silica and arsenic, nitrogen-containing organic compounds, oxidants and reductants in solution etc. 

Biomethylation may also produce more complex alkyl arsenic groups. As(C2H5)(CH3)2 has been found in landfill and sewage gas, and probably also exists in natural gas (Bentley and Chasteen, 2002), 251. As(C2H5)3 may also occur in landfill gases and probably natural gas (Bentley and Chasteen, 2002), 251. Further details on the reduction and methylation biochemistry of arsenic are discussed in Chapter 4. 

Cullen, W.R., McBride, B.C. and Reglinski, J. (1984a) The reduction of trimethylarsine oxide to trimethylarsine by thiols a mechanistic model for the biological reduction of arsenicals. Journal of Inorganic Biochemistry, 21(1), 45-60. 

Arsenic interrupts some of your body s most basic and common biochemical pathways. Arsenic, particularly As " and As + oxides, interferes with the citric acid cycle and respiration (specifically reduction of NAD-I- and ATP synthesis— see Biochemistry ). If that weren t enough to kill you, and it probably is, arsenic also boosts the level of hydrogen peroxide in your body, which causes another whole set of problems. Unfortunately, these toxic forms of arsenic are not only water soluble but can be found in well water from natural sources and man-made contamination from mining. 

Allard B, Arsenic I (1991) Abiotic reduction of mercury by humic substances in aquatic system. An important process for the mercury cycle. Water Air Soil Poll. 56 457-464 Anderson A (1979) Mercury in soils. In Nriagu JW (ed.) The biochemistry of mercury in the environment. Elsevier, Amsterdam, pp 79-112 Azzaria LM, Aftabi A (1991) Stepwise thermal analysis technique for estimating mercury phases in soils and sediments. Water Air Soil Poll 56 203-217 Azzaria LM (1967) A Method of determining traces of mercury in geologic materials. Geol Surv Can, pp 66-54. 

---