Condensed phosphate

Condensed milk Condensed phosphates Condensed whey Condenser Condensers... 

Phosphoric acid can undergo phosphate condensation, a reaction that is similar to the condensation reactions of other species that contain O—H bonds (see Chapter 13) ... 

Phosphate condensation reactions play an essential role in metabolism. Recall from Section 14.6 that the conversion of adenosine diphosphate (ADP) to adenosine triphosphate (ATP) requires an input of free energy ADP -I-H3 PO4 ATP +H2O AG° — +30.6kJ As also described in that section, ATP serves as a major biochemical energy source, releasing energy in the reverse, hydrolysis, reaction. The ease of interchanging O—H and O—P bonds probably accounts for the fact that nature chose a phosphate condensation/hydrolysis reaction for energy storage and transport. 

Carbamyl phosphate condenses with ornithine to yield citrulline in the ornithine transcarbamylase (OTC) reaction. OTC is encoded on band p21.1 of the X chromosome, where the gene contains 8 exons and spans 85 kb of DNA. The activity of this enzyme is directly related to dietary protein. There may be tunneling of ornithine transported from the cytosol to OTC, with the availability of intramitochondrial ornithine serving to regulate the reaction. 

As discussed in Chapter 2, section C2, pyridoxal phosphate condenses with amino acids to form a Schiff base (structure 8.44). Each of the three groups around the chiral carbon at the top of structure 8.44 may be cleaved to give an anion that is stabilized by delocalization of the electrons over the 7r orbitals. 

A. L. Boulle (1965). Les phosphates condenses mineraux. Aspects structuraux, Rapport Colloquium National du Centre National de la Recherche Scientrique CNRS Composes Organiques du Phos-... 

G. Dirheimer (1964). Recherches sur les phosphates condenses chez les microorganismes. Etude de leur nature et de quelques enzymes intervenants dans leur utilisation metabolique. These Doctor Physique, Universite Strasbourg, France. 

J. P. Ebel (1958). Action physiologique et toxicologique des phosphates condenses. Ann. Nutr. Aliment., 12, 59-67. 

In these transactions, electrons - often combined with protons into hydrogen atoms -are transferred from a donor to an acceptor down a difference in energy level, which is measured by the difference between the redox potentials of the two reactants. A very large number of such reactions participate in metabolism. To be able to serve for ATP regeneration, electron transfers must satisfy two conditions (1) they must release enough energy to power the reversal of Reaction 10.1 and (2) they must be coupled to the reversal of this reaction - that is, constrained in such a way that they can take place only if ADP and inorganic phosphate condense to ATP at the same time. 

Phosphorus compounds occur in wastewater under various forms, among which the reduced ones are predominant. The phosphorus compounds of wastewater concern not only some organic forms (natural or anthropic) but also orthophosphate ion and acid hydrolysable phosphate (condensed phosphate) (Fig. 10). 

N. Coumert, M. Porthault and J.-C. Merlin, Analyse Potentiometrique de Phosphates Condenses en Solution dans les Nitrates Alcalins a 350 °C, Bull. Soc. Chim. France 33 (1965) 910. 

Condensed phosphates. Condensed phosphates are those containing more than one P atom and having P—O—P bonds. We may note that the lower acids can also give condensed species, although we shall deal here only with a few examples of phosphates. 

The main pyrolysis mechanism of nucleic acids (occurring at temperatures as low as 180°C) is the expulsion of the polysaccharide moiety with the simultaneous formation of base-phosphate condensates. The base phosphate complex is further pyrolysed, yielding the base fragments. Compared with polysaccharides and lignin, the application of Py-GC/MS techniques to the analysis of nucleic acids is still in its infancy. 

This appendix provides a list of some of the most common organic phosphorus compounds found in the environment, ft also includes complex inorganic phosphates (condensed phosphates) and synthetic organic phosphates commonly used in assays of phosphatase activity. It is not an exhaustive list, but rather provides a handy... 

Otera, J., Niiho, Y. and Nozaki, H. (1991) Oxirane ring-opening with alcohol catalysed by organotin phosphate condensates. Complete inversion at tertiary and henzylic centers. Tetrahedron, 47, IClS-lCiA, Corey, E.J. and Helal, C.J. (1993) A catalytic enantioselective synthesis of chiral monosuhstituted oxiranes. Tetrahedron Letters, 34, 5227-5230. 

Some details of the distribution of label, not previously discussed, should be mentioned. The concentration of dihydroxyace-tone phosphate is considerably greater than that of phospho-glyceraldehyde. When these two similarly but not equally labeled triose phosphates condense the result is a hexose phosphate labeled more heavily in the number 4 carbon atom than in the number 3 carbon atom position. This distribution was observed experimentally by Kandler and Gibbs (1956). 

The mode of nthesis of deoxyribose is a subject of active interest at the present time. It has been shown that deoxyribose 5-phosphate can be synthesized by condensation of acetaldehyde and glyceraldehyde 3-phosphate in the presence of an aldolase from animals and bacteria (80). A pathway for deoxyribonucleotides can be formulated which employs this aldolase. The 5-phosphate ester could be converted to a l-phosphate by a mutase, the deoxypentose phosphate condensed with a base to form a nucleoside by nucleoside phosphorylase, and the nucleoside converted to a nucleotide by a kinase [Eq. (26)]. 

The former pathway has been further elucidated by Harris and Yavit 8) who demonstrated that crude yeast extracts catalyze an ATP-de-pendent reaction by which 2-methyl-4-amino-5-hydroxymethylpyrimidine phosphate condenses with the thiazole moiety to form thiamine monophosphate [Eq. (2)]. This system has been further purified by Leder (9) and the reaction has been shown to consist of condensation of the pyrophosphate of the pyrimidyl moiety with the phosphate of the thiazole moiety. Similar conclusions have been reached by Camiener and Brown... 

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