Monophosphate esters

Compared to native starches, monophosphate esters have a decreased gelatinization temperature range and swell in cold water at a DS of 0.07. Starch phosphates have increased paste viscosity and clarity and decreased retrogradation. Their properties are in many ways similar to those of potato starch, which naturally contains phosphate groups. 

The use of the triphenylphosphine-di(2-pyridyl) disulphide reagent for effecting condensation reactions has been reviewed.84 Combination of triphenylphosphine with bis(O-thiocarbonyl) disulphide gives a superior reagent compared to that mentioned above for the preparation of mixed diesters of phosphoric acid from monophosphate esters.86... 

By the reaction of D-glyceraldehyde and 1,3-dihydroxypropane (both as monophosphate ester), D-fructose as the 1,6-diphosphate ester is formed. The process is readily reversible and is catalyzed by an enzyme known as aldolase. 

Potato starch usually contains 0.01-0.6% (w/w) phosphorus. Although phosphorus is present at very low levels, it has a significant effect on the physicochemical properties of starch. Phosphorus is in part responsible for the high swelling power, paste stability, and resistance to enzyme hydrolysis of potato starch. Potato starches contain significant amounts of monophosphate esters... 

Bone contains at least two different acid phosphatases and the more abundant enzyme may function as a pyrophosphate. The physiological substrate for the latter enzyme may be pyrophosphate or another oligophosphate ester. The first enzyme may utilize only monophosphate esters. 

The enzyme catalyzes the deamination of a wide spectrum of naturally occurring adenosine derivatives including, in addition to the majority of compounds noted in Table VII, many other phosphorylated derivatives (75, 179). The Km values for adenosine, 5 -AMP, 3 -AMP, 3, 5 -cyclic AMP, and 2 -dAMP ranged from 0.1 to 0.5 mM. Except for 2 -dAMP, the relative rates of deamination for these compounds were similar. The 2 -monophosphate ester was not deaminated (75, 180). Oligomers of AMP such as ApA, ApAp, ApApA, and ApApApA (181) were also substrates deamination of the first residue of ApAp was more rapid than the second. Deamination of polyadenylic, polydeoxyadenylic, and the terminal residue of E. coli soluble RNA was not observed. 

There have been synthesized in this laboratory over the past several years a variety of phosphonic acids which are nominally isosteric with natural monophosphate esters. Of this collection of compounds three are of particular interest for the present work. These are (S)-3,4-dihydroxybutyl-1-phosphonic acid (A)(1), an isosteric analogue of sn-glycerol-3-phosphate 4-hydroxy-3-oxobutyl-l-phosphonic acid (B)( ), an isosteric analogue of dihydroxyacetone phosphate and 5-carboxy-4-hydroxy-4-methylpentyl-l-phosphonic acid (C)(3), an isosteric analogue of 5-phosphomevalonate. 

The solution of 4.3 parts vitamin B1 monophosphate hydrochloride in 16 parts of water was diluted with 11 parts 15% NaOH, 2.1 parts benzoyl chloride was dropwise added with stirring and cooling. The obtained mixture was neutralized, evaporated in vacuum, acidified with concentrated HCI to pH 3.5-4, whereupon a crude S-derivative of vitamin B-l monophosphate ester was precipitated. The product was suspended in water, was bringing with NaOH to pH 7 and was acidified to pH 4. 3.4 g refined S-benzoylthiamine O-monophosphate was prepared MP 165°C (with decomposition). 

Alkaline phosphatase Catalyzes hydrolysis of monophosphate ester groups from compounds, including from the 3 -and Y-terminal ends of nucleic acids and nucleotides. 

Like other dissolved organic nutrients, the chemical composition of organic P is relatively unknown. Marine dissolved organic phosphorus (DOP) composition has been mostly identified as particular compound classes such as monophosphate esters, phosphonucleotides, nucleic acids, phospholipids, phosphonates and polyphosphates (Benitez-Nelson, 2000). Kolowith et al. (2001) found that monophosphate esters and phosphonates are major components in the Pacific Ocean, the Atlantic Ocean and the North Sea. ATP (adenosine triphosphate), ubiquitous in aU living cells, has been used as a model DOP compound in radiotracer experiments to obtain information on P sources and fluxes in natural environments (Bjorkman et al., 2000 Karl and Bossard, 1985) and cyanobacterial cultures (Fu et al., 2006). 

Fig. 3 Plots of k0bSd versus total concentration of monophosphate ester, 10 90 dioxane/ water, 25 °C. Reproduced with permission from Ref. 90b. Copyright 1987 American Chemical Society.

Competitive inhibition can occur in freely reversible reactions owing to accumulation of products. Even in reactions that are not readily reversible, the product can function as an inhibitor. In the alkaline phosphatase reaction, in which hydrolysis of a wide variety of organic monophosphate esters into the corresponding alcohols (or phenols) and inorganic phosphates occurs, the inorganic phosphate acts... 

Fig. 9. A proposed mechanism for the catalyas of the hydrolysis of monophosphate esters by alkaline phosphatase.

Once spectra have been obtained, it is necessary to obtain valid assignments for each resonance. As a first step, comparison of chemical shifts of spectral lines with shifts of known metabolites obtained in vitro under physiological conditions (see Fig. 10) permits tentative assignments. These tentative assignments can be checked by conventional analysis of tissue extracts, to see if the amount observed in the extract corresponds to the amount indicated by the in vivo spectrum. Another approach is to obtain spectra of extracts as a function of pH, assigning on the basis of pK [17]. These approaches become less reliable as spectra become more complex (as is often the case for in vivo (see, e.g., Ref. 18) and H-NMR [19] (Fig. 16)), or broad, overlapping lines are encountered (e.g., the monophosphate ester region of P-NMR spectra). 

Such di- and triphosphate esters are also common biologically, and are even more reactive than the monophosphate esters. 

Phosphorylation. The definitive paper on the conversion of alcohols into the monophosphate esters has been published.1... 

In the hydrolysis of all these monophosphate esters, cleavage of the P—O bond occurs exclusively and in this respect resembles enzymatic reactions involving alkaline phosphatases. Although dipositive metal ions influence the hydrolysis of certain diesters of phosphoric acid, there is insufficient evidence for the postulation of chelated intermediates (186). 

Thiamine monophosphate ester phosphoric acid salt Urn-beon. Ci3H N408PjS mol wt 442.35. C 32.58%, H 4.56%, N 12.67%, O 28.94%, P 14.00%, S 7.25%. Obtained by boiling an aq soln of thiamine triphosphoric acid ester for 2 hrs Velluz et al.. Bull. Soc. Chim. France 15, 871 (1948) from thiamine phosphoric acid ester chloride hydrochloride by ion exchange Zima et al., E. Merck s Jahresber. 67, 10... 

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