Monoesters, phosphate

Monoester salts of phosphoric acid derived from fatty alcohol ethylene oxide adduct or alkylphenol ethylene oxide adduct useful as surfactants are prepared by addition of R(OCH2CH2) OH, alkali fluoride and (C12P0)20 in a molar ratio of 0.9-1.5 0.05-1 1.0 at -50 to + 10°C and hydrolysis of the Cl-containing intermediates with a base. The monoester phosphates showed comparable or better washing and foaming efficiency than commercial products [12]. 

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

With [32P]phosphoric diimidazolide, prepared from sulfinyldiimidazole or CDI and H332P04, the 5 -terminal monoester phosphate groups in various RNAs could be selectively phosphorylated (radioactive labeling method) 1571,1581... 

Firestone and Heath442 found that the alkaline phosphatase (ortho-phosphoric monoester phosphate hydrolase, EC 3.1.3.1) that is induced in cultured cells by dibutanoy 1-cAMP is not detectable in the presence of inhibitors of glycosylation, although messenger RNA is found in proportions that are comparable to those of noninhibited... 

Pro-prochiral substrate giving pro-pro-prochiral product (i.e., monoester — phosphate). 

Matrix Effects. pH. Numerous factors such as sample pH, ionic strength, humic substances, and relaxation agents can modify the NMR spectrum. For example, monoester phosphate chemical shifts are pH-de-pendent (44-46), and we showed (44) for several monoester phosphates that as the sample pH is increased, their chemical shifts also increase (Figure 3). This behavior is caused by the ability of monoester phosphates to undergo protonation-deprotonation. Because the monoester phosphate chemical shift is pH-dependent, the curves resulting from plotting pH versus chemical shift are analogous to a titration curve. Thus, monoester phosphate pKa values can be measured from these pH-chemical shift curves (44-46). 

Figure 3. Effect of pH on the chemical shift of several monoester phosphate compounds. Serine phosphate and inositol monophosphate are in a pure water matrix, and adenosine monophosphate is in a concentrated humic-FeEDTA...

Although the characterization of DOP in rivers and estuaries has been largely ignored, some work in the Mississippi River indicated that the composition of SNP primarily consisted of diester and monoester phosphates, phosphonates, orthophosphates, and/or tri- and tetrapolyphosphates. 

Concerning the oxygen-containing bidentate ligands [R E02+ ] and MC, discrete dimeric, tetrameric and hexameric ring assemblies have been reported for organotin carboxylate, phosphinate, phosphonate monoester, phosphate diester, " sulfonate, and tungstate derivatives. 

The lowest Mr fraction, OS-3, was in fact a mixture of core-related linear molecules (Fig. 6) containing a minimal disaccharide composed of the innermost LD-Hep (phosphorylated) and its neighboring Kdo residue, and three more extended glycans that allowed for the determination of the core OS backbone. The backbone of the core OS of H. pylori type strain was composed of a phosphorylated (monoester phosphate) hexasaccharide in which the typical core sugars, LD-Hep, Glc, and Gal, were present, but, in addition, this core OS also possessed the less common DDHep as a constituent. 

Hep. The P NMR spectra and the linkage analysis data suggested the presence of a monoester phosphate (PO4) at the Q-1 position of the inmost LD-Hep of the strains described here, except in strain R-7A, where a 2-aminoethyl phosphate was shown to replace the monoester phosphate, as in //. pylori Sydney strain (Section IV). 

All cores share a similar structure. However, the inner most LD-Hep unit may either carry a monoester phosphate or a 2-aminoethyl phosphate at position 0-7. 

This seemingly small isotope effect must be compared to the isotope effect measured for the hydrolysis of the dibenzyl ester precursor to the isotopically labeled monoester [phosphate triesters can only hydrolyze by an Sn2(P) mechanism], 1.0070 -I- 0.0038, for proper interpretation. The fact that the hydrolysis of the monoester has a larger isotope effect was interpreted as demonstrating that substantial cleavage of the phosphate ester bond occurs in the transition state this is in accord with the expectation based on an Sn 1(P) mechanism. 

Phosphate monoesters, phosphate diesters and phosphonates soluble or sorbed to soil particles. 

Uncatalyzed Reactions of Phosphate Monoesters. Phosphate monoesters in physiologically relevant pH ranges exist as either the monoanion or dianion. A large body of evidence indicates that uncatalyzed phosphoryl transfer reactions of both ionic forms takes place by loose transition states that are characterized by extensive bond cleavage to the leaving group and a small degree of bond formation to the nucleophile (for reviews of the evidence, see References (3,4)). Despite loose transition states, these reactions are concerted, and free metaphosphate is not formed in protic solvents (5). 

Structure of Coemyme A. The elucidation of the structure of CoA depended heavily on d radation by specific enzymes. The phosphate on carbon 3 of the adenosine was shown to be a monoester phosphate by hydrolysis with prostate phosphomonoesterase. The localization of the monoester at the 3 position was established by its sensitivity to a b nucleotidase that attacks only nucleoside 3 -pbosphates, not 2 - or 5 -phosphates. The original CoA molecule or the phosphatase product, depbospho CoA, can be split by nucleotide pyrophosphatases from potato or snake venom. These reactions permitted the identification of the adenosine phosphate portion of the molecule. The position of the phosphate on pantothenic acid cannot be determined enzymatically, but was established by studies on the synthesis of CoA from synthetic phos-phorylated pantetheines. Pantetheine is split to thiolethanolamine and pantothenic acid by an enzyme found in liver and kidney. This enzyme also attacks larger molecules, including CoA. 

Snake venom phosphodiesterase does not attack dinucleotides in which a free phosphomonoester occurs on a 3 position. Several phosphomono-esterases exist that can remove monoester phosphates from these and, indeed, from RNA. 

Experiments with labeled glucose, phosphate, and nicotinamide indicate that there is a rapid equilibrium between the oxidized and reduced forms of DPN (212). In a study of the incorporation of phosphate into the different pyridine nucleotide coenzymes, it was found, surprisingly, that there was a rapid turnover of the monoester phosphate grouping of TPNH. This finding contrasts with a much slower turnover of the pyrophosphate grouping of the molecule. Although there is a rapid regeneration of the monoester phosphate, there appears to be a slow equilibrium between DPN and the DPN portion of TPN. 

The monoester phosphates of PtdIns3P and PtdIns4P accounted for 95-97% of the P label in PtdInsP species. The 3- and 4-monoester phosphates accounted for 40% and 60% respectively of the label in PtdIns(3,4)P hereas the 4- and 5-monoester phosphates of PtdIns(4,5)P2 accounted for 3S and 61% respectively. 

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