Phosphorus in biology

In mammalian systems the chemistry of phosphorus is entirely that of the P(V) oxidation state and the whole of biology revolves around phosphate and its derivatives phosphate esters (polyphosphates such as ATP, phosphoamino acids, phosphosugars), phosphate precipitation (mineralised tissues, apatite) and phosphate solubilisation (utilisation of stores) Why is P(V) the only oxidation state observed Firstly phosphorus in the form of soluble phosphates are readily available to all forms of life whereas reduced forms are not available. Secondly, from the oxidation state diagram (Fig. 1) it is evident that P(V) is a very stable oxidation state and very strong reducing agents are required to reduce 

P( (E P04 /PH3 ca - 0.4 Conversely, even weak oxidising agents will oxidise PH3 all the way to H3PO4. 

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Phosphorus, in biological samples, determination by monochromatic x-ray absorption-edge method, 299-301 in ceramic materials, determination by x-ray emission spectrography, 222 in phosphate rocks, determination by x-ray emission spectrography, 260, 261... 

Jackson, G. A. and Williams, P. M. (1985). Importance of dissolved organic nitrogen and phosphorus in biological nutrient cycling. Deep Sea Res. 32, 223-235. 

The use of test kits to determine phosphorus in biologically treated sewage has been discussed by Ruider and Spatzierer [57],... 

Substitution (type nucleophilic) reactions in which an electron-rich agent (or nucleophile) attacks and forms a transient or stable bond with an electron-poor center (often carbon or phosphorus in biological systems) which has undergone prior or simultaneous expulsion of the leaving group (or exiphile). 

PHOSPHORUS (In Biological Systems). Phosphorus is required by every living plant and animal cell. Deficiencies of available phosphorus in soils are a major cause of limited crop production, Phosphorus deficiency is probably the most critical mineral deficiency in grazing livestock. Phosphorus, as orthophosphate or as the phosphoric acid ester of organic compounds, has many functions in the animal body. As such, phosphorus is an essential dietary nutrient. 

It is well known that pentacovalent cyclic phosphorus compounds play an important role as intermediates in reactions involving nucleophilic attack on tetracoordinated phosphorus in biological systems. According to this background it appears to us that it is important to prepare the arsenic derivatives, which are more stable than the corresponding phosphorus compounds and allow the study of their conformation. 

The interest in all these themes really is not decreasing, indeed some fascinating areas of research are emerging or are the subject of many investigations the medicinal chemistry of bisphosphonates, the role of phosphorus in biology, phosphorus ligands in radiopharmaceutical chemistry, phosphorus in material science, new polymers and dendrimers incorporating phosphorus, and asymmetric catalysis to name but a few. 

The method involving the Mo-V-P acid has been used in determinations of phosphorus in biological tissues [127], plant material [128], fruits [129], fish products [130], foodstuffs [131], phosphate minerals [132], cast iron and steel [133,134], niobium, zirconium and its alloys, titanium and tungsten, aluminium, copper, and white metal [135], nickel alloys [134,135], metallurgy products [136], molybdenum concentrates [137], silicon tetrachloride [7], cement [138], and lubricants[139]. The flow injection technique has been applied for determining phosphate in minerals [140] and in plant materials [141]. 

Special procedures for eliminating interference by phosphorus in biological samples analyzed by the molybdate method were developed by McGavack, Leslie, and Kao (412) and by King (413). 

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