Phosphate storage

Zaiss, U. Physiological and ecological sliidies on the regulation of phosphate storage of Oscillatoria redekei. I. enzyme kinetics of polyphosphate kinase. Arch. Hydrobiol. Suppl., 72, 49-80 (1985)... 

In his rejection of the Emerson model, Rabinowitch went on to say The difficulty of the phosphate storage theory appears most clearly when one considers the fact that, in weak light, eight or ten quanta of light are sufficient to reduce one molecule of carbon dioxide. If each quantum should produce one molecule of high-energy phosphate, the accumulated energy would be only 80-100 kcal per Einstein—while photosynthesis requires at least 112 kcal per mole, and probably more, because of losses in irreversible partial reactions (Vol. 1, p. 228). 

Thecells of protozoa (Docampo and Moreno, 2001) and alga Chlamydomonas reinhardtii (Ruiz etal, 200 lb) possess specific PolyP and Ca2+ storage organelles, i.e. acidocalcisomes, which are similar to vacuoles in some properties, especially in the presence of protonpumping pyrophosphatase. These organelles act as phosphate storage systems for the above lower eukaryotes. 

In the course of evolution from prokaryotes to eukaryotes, the energetic role of PolyP decreased. However, other functions came to the fore, such as phosphate storage, cation chelation, regulation of enzyme activities, gene expression and membrane transport (Figure 10.6). The significance of the regulatory functions of PolyP increased in eukaryotes. 

V. U. Zaiss (1985). Physiological and ecological investigation on the regulation of phosphate storage... 

Williams, J. C. (1985). Glutamyl ribose-5-phosphate storage disease Clinical description and characterization of stored material. In ADP-Ribosylation of Proteins (Althaus, F. R., Hilz, H., Shall, S., Eds.), pp. 167-177. Springer-Verlag, Berlin. 

While research has shown that the iron oxyhydroxide cores in animal ferritins have the sole purpose of acting as iron storage sites, phosphate can also be associated with these cores and the levels depend on local conditions. In the case of bacterioferritins the native cores always seem to incorporate phosphate and there is some debate as to whether the molecules also perform the further function of phosphate storage. Interestingly, the cavity of bacterioferritins such as those from Eschirichia coli can also be used as a reaction vessel to lay down a variety of other mineral cores. Studies indicate that while details of the protein sequence and structure can vary, overall ferritin proteins can be regarded as possessing a constant set of structural motifs and it is these which are of particular relevance to coordination chemistry. 

The ADP thus formed can be converted to ATP by adenylate kinase which catalyzes the reaction 2ADP ATP -I- AMP and thus simultaneously regenerates the acceptor molecule AMP for the earlier reaction [25-28]. Thus, polyphosphate is not only a phosphate storage system but can also act as an energy resource, although only for short terms of energy deprivation. 

Another example from a significant but often overlooked market is the feed additive industry. Phytase is an enzyme added to feed enabling swine and poultry to utilize the typical plant phosphate storage compound phytic add... 

Williams JC, Chambers JP, Liehr JG (1984) Glutamyl ribose 5-phosphate storage disease. A hereditary defect in the degradation of poly(ADP-ribosylated) proteins. J Biol Chem 259 1037-1042... 

Glutamyl Ribose-5-Phosphate Storage Disease Clinical Description and Characterization of the Stored Material... 

Glutamyl Ribose-5-Phosphate Storage Disease Phosphodiesterase... 

Phytic acid, myo-inositol hexakis (dIhydrogen phosphate), as-l,2,3,S-tnns-4,6-cyclohexanehexol-hexaphosphate a major phosphate storage compound in plants, which is especially abundant in oil seeds, legumes and cereal grains. It is the hexaphosphate of A/yo-inositol (see), in which each OH-group of myoinositol is esterified with phosphoric acid. Calcium and magnesium salts of P.a. are known as phytin. The commercial preparation of myo-inositol involves extraction of P. a. from com (maize) steep liquor, hydrolysis of the P.a. to myo-inositol and inorganic phosphate, and crystallization of the myo-inositol from water. 

Cd has also been shown to induce cardiac damage in experimental settings by two possible mechanisms (i) disruption of tissue stmcture and integrity (ii) effects on cardiac conduction (reviewed in [5]). These effects were thought to be related to (i) decreased high-energy phosphate storage in the myocardium, (ii) reduced myocardial contractility, (iii) diminished excitability of the cardiac conduction system, and (iv) a reduction in coronary blood flow by Cd in isolated heart studies due to direct actions on the coronary vasculature [340]. 

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