Phosphate form

Further steps m glycolysis use the d glyceraldehyde 3 phosphate formed m the aldolase catalyzed cleavage reaction as a substrate Its coproduct dihydroxyacetone phosphate is not wasted however The enzyme triose phosphate isomerase converts dihydroxyacetone phosphate to d glyceraldehyde 3 phosphate which enters the glycol ysis pathway for further transformations... 

Triacylglycerols arise not by acylation of glycerol itself but by a sequence of steps m which the first stage is acyl transfer to l glycerol 3 phosphate (from reduction of dihy droxyacetone 3 phosphate formed as described m Section 25 21) The product of this stage IS called a phosphatidic acid... 

The 7 glutamyl phosphate formed m this step is a mixed anhydride of glutamic acid and phosphoric acid It is activated toward nucleophilic acyl substitution and gives glutamine when attacked by ammonia... 

Complex Ion Formation. Phosphates form water-soluble complex ions with metallic cations, a phenomenon commonly called sequestration. In contrast to many complexing agents, polyphosphates are nonspecific and form soluble, charged complexes with virtually all metallic cations. Alkali metals are weakly complexed, but alkaline-earth and transition metals form more strongly associated complexes (eg, eq. 16). Quaternary ammonium ions are complexed Htde if at all because of their low charge density. The amount of metal ion that can be sequestered by polyphosphates generally increases... 

Multilayers of Diphosphates. One way to find surface reactions that may lead to the formation of SAMs is to look for reactions that result in an insoluble salt. This is the case for phosphate monolayers, based on their highly insoluble salts with tetravalent transition metal ions. In these salts, the phosphates form layer stmctures, one OH group sticking to either side. Thus, replacing the OH with an alkyl chain to form the alkyl phosphonic acid was expected to result in a bilayer stmcture with alkyl chains extending from both sides of the metal phosphate sheet (335). When zirconium (TV) is used the distance between next neighbor alkyl chains is - 0.53 nm, which forces either chain disorder or chain tilt so that VDW attractive interactions can be reestablished. 

Although zirconium phosphate is insoluble in acids, it is easily hydrolyzed in excess caustic to give hydrous zirconium oxide. Zirconium phosphate forms soluble complexes with a large excess of zirconium oxide chloride, and therefore separation of phosphoms from zirconium oxide chloride solutions is difficult (215). 

FIGURE 18.27 Pyridoxal-5-phosphate forms stable Schiff base adducts with amino acids and acts as an effective electron sink to stabilize a variety of reaction intermediates. 

The mechanism of succinyl-CoA synthetase is postulated to involve displacement of CoA by phosphate, forming succinyl phosphate at the active site, followed by transfer of the phosphoryl group to an active-site histidine (making a phosphohistidine intermediate) and release of succinate. The phosphoryl moiety is then transferred to GDP to form GTP (Figure 20.13). This sequence of steps preserves the energy of the thioester bond of succinyl-CoA in a series of high-energy intermediates that lead to a molecule of ATP ... 

Regeneration was based on removing ammonium dihydrogen phosphate, formed in hydrogenolysis of benzocaine, from the catalyst. The catalyst was... 

First comes the pretreatment stage. After rust removal and alkaline degreasing, a zinc phosphate formulated pretreatment (see Section 15.2) is applied by dip or spray-dip. Crystalline iron-rich zinc phosphate forms on the metal surface at a coating weight of 0.5-4.5 g/m. ... 

The unknown phosphate ester had the same electrophoretic mobility as 2-deoxy ribitol 5-phosphate and it seemed reasonable to expect that in the conditions used (0.1 M pyridinium acetate buffer of pH 5) 2-deoxy ribitol-4- and -5-phosphates would behave similarly therefore it was considered probable that the unknown phosphate ester is 2-deoxy ribitol 4-phosphate, resulting from the reduction of the periodate resistant 2-deoxy ribose 4-phosphate. However, the possibility that both 2-deoxy ribitol 4-phosphate and 2-deoxy erythritol 3-phosphate (formed from... 

Sodium carboxymethyl chitin and phosphoryl chitin had most evident influences on the crystallization of calcium phosphate from supersaturated solutions. They potently inhibited the growth of hydroxyapatite and retarded the rate of spontaneous calcium phosphate precipitation. These chitin derivatives were incorporated into the precipitate and influenced both the phase and morphology of the calcium phosphate formed (flaky precipitate resembling octacalcium phosphate instead of spherical clusters in the absence of polysaccharide) [175]. 

C21-0088. Trisodium phosphate forms strongly basic solutions that are used as cleansers. Write balanced equations that show why Na3 PO4 solutions are strongly basic. Include p values to support your equations. 

Trialkyl phosphates form volatile 1 1 adducts with acids such as nitric and chloroacetic, from which the esters are recovered by base treatment. I.r. and n.m.r. spectral data suggest that these are hydrogen-bonded complexes. At low temperatures, in FSOaH-SbFj, trialkyl phosphates were shown (by n.m.r.) to give protonated species in which there appears to be considerable pir-d-rr back-donation from oxygen to phosphorus. These species are not stable the tri-n-butyl ester decomposing over the course of two days to MeaC+ and (HOiP. ... 

Gerke J. Humic (organic matter)-Al(Fe)-phosphate complexes an underestimated phosphate form in soils and source of plant-available phosphate. Soil Sci. 2010 175 417 25. 

Phosphate reacts and forms insoluble compounds with many metals, particularly iron, aluminum, and calcium. Under acid soil conditions, both iron and aluminum become more soluble, and thus as soil pH decreases, its phosphate fixing power increases. This means that iron and aluminum react with phosphate to form insoluble species that are not available to plants. Under basic conditions, high concentrations of calcium exist and insoluble calcium phosphates form. Insoluble phosphate species are also formed with other metals that happen to be present however, the three mentioned are generally present in the highest concentration, and so they represent the major reactants with phosphate. Iron, aluminum, and calcium phosphates can also occur as coatings on soil particles. 

Thus, the calcium di (n-decyl) phosphate forms an equilibrium with its ions at every membrane surface ... 

The cavitands are essentially synthesized from their resorc[4]arene precursors which are readily obtained by resorcinol condensation with aldehydes. The main feature comes from the different configurations that are expected for this tetrameric species and the relative thermodynamical stability of each isomer, which has been widely investigated by several authors. In addition, the conformational mobility of the resorc[4]arene molecules will depend on substitution at the upper and lower rims [28, 36, 40, 41]. The first attempt to synthesize a phosphorus bridged cavitand was to treat resorc[4]arene la (1, R=CH3) with phenylphosphonic dichloride or phenylphosphonothioic dichloride. Only inseparable isomer mixtures were obtained and isolation of the desired cavitands was not possible [42]. The first isolated phosphorylated resorcinol-based cavitand was described in 1992 by Markovsky et al., who prepared compound D from la and four equivalents of o-phenylenechlorophos-phate in the presence of triethylamine [43, 44]. For this compound, a tautomeric temperature and solvent dependent equilibrium exists between the spirophosphorane structure and the cyclic phosphate form (Scheme 4). 

The coupling led to the intermediate phosphite (step a) which was oxidized by TBHP (step b). The phosphate formed containing eight ethoxy groups was deprotected by trans-esterification using trimethylbromosilane and subsequent hydrolysis by water (step c). Two benzoyl groups were removed by basic hydrolysis (step d). The same tetrakis phosphate was prepared by phosphitylation with dibenzyl-h/,iSr-diisopropylphosphoroamidite in the presence of tetrazole (step c) followed by oxidation with CPBA (step f). The removal of all benzyl and benzoyl groups was achieved in one step by sodium in liquid ammonia (step g). 

A lysine residue reacts with the carbonyl of dihydroxyacetone phosphate, forming first an addition product that dehydrates to give an imine linkage. 

In resting muscle, creatine phosphate forms due to the high level of ATP. If there is a risk of a severe drop in the ATP level during contraction, the level can be maintained for a short time by synthesis of ATP from creatine phosphate and ADP. In a nonenzymatic reaction [6], small amounts of creatine and creatine phosphate cyclize constantly to form creatinine, which can no longer be phosphorylated and is therefore excreted with the urine (see p. 324). 

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