Enzymatic dephosphorylation

The phosphorylated glucose (G-6-P) occupies a key position in carbohydrate metabolism and can be utilized by 4 main pathways (a) by glucose release following enzymatic dephosphorylation (b) by... 

From this detailed kinetic analysis of the complex pH dependence for the chemiluminescence intensity we conclude that only the enzymatic dephosphorylation of AMPPD... 

Thornton K, Smith AM, Merry CLR, Ulijn RV (2009) Controlling stiffness in nanostructured hydrogels produced by enzymatic dephosphorylation. Biochem Soc Trans 37 660-664... 

N-terminal dodecapeptide from EDP208 pili /V -Ac-Thr-Asp-Leu-Leu-Ala-Gly-Gly-Lys /V -[Bz(4-N,)])-Asp- by iodination and enzymatic dephosphorylation post-SPPS with Bz(4-N3)-OSu [45]... 

Entry 7 in Table 3.36 is a rare example of the use of a phosphodiester as a linker for alcohols. This linker, when used in combination with an enzyme-compatible support, can be selectively cleaved with a phosphodiesterase. To obtain the free alcohol, the released phosphate must be subjected to an additional enzymatic dephosphorylation. 

Perlmann, G.E. 1952. Enzymatic dephosphorylation of ovalbumin and plakalbumin. J Gen Physiol 35 711-726. 

In addition, there have been some recent applications of FruA in the field of pheromones [17]. The two independent stereogenic centers of the condensation product were stereospecifically generated by FruA-catalyzed aldol addition of 5-oxohexanal to DHAP. Further, enzymatic dephosphorylation and a series of straightforward chemical transformations yielded (-i-)-exo-brevicomm, the sex aggregation pheromone of the bark beetle. 

Horita, A. and L. J. Weber. 1961. The enzymatic dephosphorylation and oxidation of psilocybin and psilocin by mammalian tissue homogenates. Biochemical Pharmacology 7 47-54. 

Nucleosides can be analysed by conventional reversed-phase (RP) LC with a buffered mobile phase. The separation of nucleotides is somewhat complicated by the dissociation of the phosphate groups and HINa exchange at these sites. As indicated for the phosphorylated anabolites of nucleoside reverse transcriptase inhibitors (NRTI, Ch. 13.2.4), ion-pair RPLC using 7V,7V-dimethylhexylamine (DMHA) can be applied to both reduce adduct formation and obtain sufficient retention [6-7]. Alternatively, enzymatic dephosphorylation of the nucleotides prior to LC-MS analysis can be performed. 

One of the best examples of an enzymatic dephosphorylation for a synthetic purpose is shown in the entry 5 ofTable 13-6. A 5 -ribonucleotide phosphohydrolase was used in the synthesis of (-)-aristeromycin, a carbocyclic analog of adenosine. The (-)-enantiomer of aristeromycin shows some cytostatic and antiviral activity, while the (+)-enantiomer is inactive. The racemate ( )-5 -phosphorylated aristeromycin was resolved by selective hydrolysis of the (-)-enantiomer with the hydrolase. The (-)-alcohol and the (+)-5 -phosphate derivative were separated easily on a silica gel column. Hydrolysis of the (-t-)-enantiomer with calf intestinal phosphatase yielded pure (+)-alcohol. 

The remainder of our discussion on phosphoproteins will deal with the types of enzymes involved in phosphorylation of nonenzyme proteins, substrate specificity of those enzymes, and enzymatic dephosphorylation of phosphoproteins. 

Fig. 2. Inhibition of enzymatic dephosphorylation of serine- and threonine-0-phosphate residues in proteins by toxins.

As usual, standard syntheses of nucleotides are not included in this survey. Using adenosine 5 -[(i )- 0, 0, 0]phosphate, it has been shown that the conversion of adenosine 5 -phosphate to cyclic AMP and the enzymatic hydrolysis of the latter to the former both occur with retention of configuration at phosphorus. Cyclic AMP can be used to prepare 2 -0-substituted adenosine derivatives 2 -0-succinyl adenosine was synthesized by acylation followed by enzymatic dephosphorylation on equilibration the 3 -0-succinyl isomer was slightly favoured (54%). ... 

Similarly, the product from a DHAP-depending aldolase-catalyzed reaction is a chemically labile 2-oxo-l,3,4-triol, which is phosphorylated at position 1. Dephosphorylation under mild conditions, without isolation of the intermediate phosphate species, by using acid phosphatase is a method frequently used to obtain the chiral polyol products [512-515]. As shown in Scheme 2.76, enzymatic dephosphorylation of the aldol product obtained from 5-substituted hexanal derivatives under mild conditions gave the sensitive chiral keto-triol in good yield. In this case the product could be transformed into (-i-)-exo-brevicomin, the sex pheromone of the pine bark beetle. 

An elegant synthesis of (+)-exo-brevicomin, the sex pheromone of the bark beetle made use of FDP-aldolase (Scheme 2.188) [1402]. RAMA-catalyzed condensation of DHAP to a 8-keto-aldehyde gave, after enzymatic dephosphorylation, a f/treo-keto-diol, which was cychzed to form a precursor of the pheromone. Finally, the side chain was modified in four subsequent steps to give (+)-exo-brevicomin. 

Figure 27.4 Chemiluminescence of CDP-5/ar. Enzymatic dephosphorylation of dioxetane by alkaline phosphatase leads to the formation of the metastable dioxetanephenolate anion which decomposes and emits light at 466 nm (adapted from CDP-5/ar product sheet available at https // e-labdoc.roche.com/LFR PublicDocs/ras/11759051001 en 08.pd0-...

Borner and coworkers used acid phosphatase to induce microstructure formation. The peptide-segment contained three phosphothreonine residues in the (TV)s peptide motif of the peptide-PEO conjugate, which prevented p-sheet formation. Enzymatic dephosphorylation of the threonine side chains therefore induced self-assembly of the bioconjugate. 

Figure 1.50 uses P-casein as an example to show that the solubihty of a phosphoprotein in the presence of calcium ions is greatly improved by partial enzymatic dephosphorylation. 

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