Pyrophosphate triphosphate

In addition to substrates noted in Table VII, 3 -AMP, 3, 5 -cyclic AMP, dATP, dADP, dAMP, ADPribose, ADPglucose, 5 -adenosine monosulfate, 5 -adenosine acetate, 5 -adenosine propionate, NAD, FAD, CoA, and nucleosidin were deaminated at appreciable rates. Deamination of ATP was inhibited by orthophosphate, pyrophosphate, triphosphate, and Fe3+ with adenosine none of these substances were effective inhibitors. Effects of other divalent cations were not reported. 

Quantitative estimation of the compounds of simple mixtures of phosphates, polyphosphates, and polymetaphosphates can be effected without too much difiSculty. Determinations of orthophosphate, pyrophosphate, triphosphate, and so-called hexametaphosphate" are usually made on mixtures of soluble phosphates. Total phosphorus content is also determined by hydrolyzing all other phosphates to orthophosphoric acid. No distinctive analytical methods are, however, available for the direct quantitative determination of the cyclic metaphosphates. 

Sodium pyrophosphate, triphosphate and oligophosphates such as glassy metaphosphates are used frequently in conjunction with alkali metal carboxylate soaps. They soften hard water which would otherwise cause precipitation of insoluble calcium and magnesium soaps, and they increase lathering power. 

If the reaction mixture had contained an effective ligand such as pyrophosphate, triphosphate, or citrate (concentration 5 x 10 M), F would have been over 90 and would have decreased very little in several weeks. These substances can compete with OH" for chromium(III) and thus prevent the polymerization. 

Ligases (syniheiases). Enzymes catalysing the joining together of two molecules coupled with the hydrolysis of a pyrophosphate bond in ADP or a similar triphosphate. They include some carboxylases and many enzymes known as synthetases. 

AMP, ADP, and ATP = adenosine mono-, di-, and triphosphate IMP = inosine 5 -monophosphate AICAR = 5 -phosphoribosyl-5-amino-4-imida2olecarboxamide DAP = diaminopimelic acid PRPP = phosphoribosyl pyrophosphate a — KGA = a-ketoglutaric acid Orn = ornithine Cit = citnilline represents the one carbon unit lost to tetrahydrofolate as serine is converted to glycine. 

In E. coli GTP cyclohydrolase catalyzes the conversion of GTP (33) into 7,8-dihydroneoptetin triphosphate (34) via a three-step sequence. Hydrolysis of the triphosphate group of (34) is achieved by a nonspecific pyrophosphatase to afford dihydroneopterin (35) (65). The free alcohol (36) is obtained by the removal of residual phosphate by an unknown phosphomonoesterase. The dihydroneoptetin undergoes a retro-aldol reaction with the elimination of a hydroxy acetaldehyde moiety. Addition of a pyrophosphate group affords hydroxymethyl-7,8-dihydroptetin pyrophosphate (37). Dihydropteroate synthase catalyzes the condensation of hydroxymethyl-7,8-dihydropteroate pyrophosphate with PABA to furnish 7,8-dihydropteroate (38). Finally, L-glutamic acid is condensed with 7,8-dihydropteroate in the presence of dihydrofolate synthetase. 

FIGURE 3.9 The triphosphate chain of ATP contains two pyrophosphate linkages, both of which release large amounts of energy upon hydrolysis. 

BIs-triethylammonium pyrophosphate Adenosine triphosphate Bis(trimethylsilyl) acetamide Cefaclor Cefroxadine Ceftizoxime... 

The sodium salts of these acids, sodium pyrophosphate (Na4 P2 O7) and sodium triphosphate (Nas P3 Oio), have been used widely in detergents. The polyphosphate anions are good additives for cleansing agents because... 

Ligases (synthetases) - catalyzing the condensation of 2 molecules coupled with the cleavage of a pyrophosphate bond of ATP or similar triphosphate. 

GA-3-P = glyceraldehyde 3-phosphate TPP = thiamine pyrophosphate DOXP = 1-deoxy-D-syiuiose CTP = oytosine triphosphate ATP = adenosine triphosphate ... 

Access to diphosphates (pyrophosphates) and triphosphates is provided through the reaction of phosphoric mono- or diimidazolides with a monoester phosphate. 

Nucleoside triphosphates are prepared analogously to the diphosphates by the methods a, b, c, and d, representing conversion of a nucleoside phosphoric azolide with inorganic pyrophosphate (Method a), of a nucleoside diphosphoric azolide with inorganic phosphate (Method b), of a phosphoric bisazolide with a nucleoside diphosphate (Method c), and of a diphosphoric bisazolide (bisazolide of pyrophosphoric acid) with a nucleoside phosphate (Method d). 

Such enzymes catalyse the condensation of specific compounds, accompanied by the breakdown of a pyrophosphate bond in adenosine triphosphate (10.64). Adenosine is the condensation product of a pentose (D-ribofuranose) and a purine (adenine). Scheme 10.15 shows the action of glutamine synthetase on a mixture of L-glutamic acid (10.65) and... 

In all the experiments, the main decomposition products were phosphonates, which are also stable in concentrated solutions of Mg and Ca chlorides. In some experiments, pyrophosphate, and in smaller amounts triphosphate, could also be detected. The authors thus assume that the primeval ocean contained phosphonates as a source of phosphorus for reactions leading to biochemically relevant molecules. Iron meteorites could have delivered sufficient reduced phosphorus (Fe3P) to the primeval Earth, so the question of prebiotic phosphorus chemistry should be looked at in more detail in the future (Pasek and Lauretta, 2005). 

These transport systems use a primary source of energy to drive active transport of a solute against a concentration gradient. Primary energy sources can be chemical, electrical and solar. In this section, systems will be described mainly that hydrolyse the diphosphate bond of inorganic pyrophosphate, ATP, or another nucleoside triphosphate, in order to drive the active uptake of solutes. Transporters using another primary source of energy will be briefly mentioned. 

---