Phosphate substitution

Modifications at the phosphorous center, including the phosphorothiolate, methylphos-phonate, and phosphoramidate derivatives, have generally shown reduced binding affinity for their RNA targets [19]. Replacement of the phosphate generally destabilizes bind- 

---

Finally, Droge and coworkers26 showed that the 2-aminoethyl phosphate-substituted KDO group is the lateral KDO unit of the branched trisaccharide (see Fig. 7), as follows. LPS from Salmonella minnesota mR3 was subjected to periodate oxidation. This sample, together with a control that had not been oxidized, was then mildly hydrolyzed with acid (pH = 3.4) during 1 h at 100°. Following removal of lipid A, both samples were analyzed by gel-filtration on Sephadex G-10, and paper electrophoresis. As expected, the ninhydrin-positive material obtained from the control sample was identical with KDO 7-(2-aminoethyl phosphate) (17) as previously identified. This spot was absent from the periodate-treated sample. Instead, an almost neutral, ninhydrin-positive spot was observed. This material (compound 26) was eluted, subjected to reduction with sodium [3H]borohydride, and hydrolyzed under strongly acidic conditions (see Scheme 11). Fol-... 

Gore and co-workers developed a convenient experimental procedure for the conversion of a-phosphate-substituted allene 103 to the preferentially formed E-config-ured 1,3-pentadiene 105 (Eq. 14.13) [46, 47, 51]. In a similar manner, Vermeer and co-workers converted a-acetate-substituted allenes 106 into the corresponding 1,3-dienes 107 in moderate to good yields by simple treatment with organozinc chlorides in the presence of Pd(0) catalyst (Eq. 14.14) [52]. 

The current uses of sodium sulfate include detergents (45%, as a phosphate substitute), textiles (18%), kraft sulfate pulping (13%), and glass (10%). 

Blennow, A., Wischmann, B., Houborg, K., Ahmt, T., Madsen, F., Poulsen, R, Jergensen, K., Bandsholm, O. (2005b). Structure - function relationships of transgenic starches with engineered phosphate substitution and starch branching. Int. J. Biol. Macromol, 36, 159-168. 

Several cases have been documented in which a different, naturally occurring, glycosyl phosphate substitutes for the true substrate of the pyrophosphorylase. Adenosine 5 -(a-D-xylopyranosyl pyrophosphate) was prepared by the action of the pyrophosphorylase of adenosine 5 -(a-D-glucopyranosyl pyrophosphate) from wheat flour,218... 

BETZ Laboratories of Trevase, PA has developed an inorganic phosphate substitute for chromate corrosion inhibitors called Dianodic Q, which is used in 10 to 20 ppm concentrations in cooling water. 

Aldonic acid phosphates substituted at the two position retained inhibitory activity but substitution at the three position destroyed inhibitory activity. 

Beside these inorganic ligands there are also organic ligands like humic or fulvic acids, which occur naturally in almost all waters, but also NTA and EDTA, which enter the hydrosphere as phosphate substitutes in detergents (Bernhardt et al. 1984) and can mobilize metals. 

In addition to its use as a selective adsorbent and powerful desiccant, zeolite A has turned out to be a highly efficient remover of calcium ions and in powder form is the preferred phosphate substitute in certain detergent formulations. 

Most metal phosphates are insulators however, phosphate substitution has been demonstrated in some notable conducting oxides. For example, superconducting MBaSrCu2.8(P04)o.206.2 (M = La-Ho, Y) analogs of YBa2Cu30y (see Superconductivity) have been prepared, with critical temperatures up to 38 K. ... 

Zeolite A, the most important phosphate substitute, became the highly demanded builder worldwide. The worldwide production of zeolite A increased in western Europe in the 1990s. Determent builder zeolites represent the largest application field for zeolite. Almost 90 percent of zeolites produced worldwide (or 215,000 tons/year) in 2003 were used for detergents. Meanwhile, production capacities for detergent-grade zeolites have largely surpassed the demand [4]. 

At the same time, the industry embarked on an intensive search for phosphate substitutes. Of a very large number of experimental organic builders, a few substances reached commercialization or near-commercialization, including trisodium nitrilotriaceate (NTA), trisodium carboxymethoxysuccinate (CMOS) (181) and trisodium carboxymethyltartronate (182). As discussed above, sodium citrate ether carboxylates have achieved widespread use as phosphate substitutes. Polymeric builders (polyelectrolytes) proved to be effective calcium sequestrants, but failed to satisfy the criterion of acceptable biodegradability. Interestingly, some monomeric polycarboxylates proved to be even more powerful calcium sequestrants than sodium tripolyphosphate but were not sufficiently biodegradable (183). 

Interest in phosphorus-containing calixarenes continues. Structures reported include hexa(diethoxyphosphoryloxy)calix[6]arene (8), inherently chiral 1,2-bridged calix[4]arene diphosphates, and a calixarene like C3 symmetric receptor with a phosphate function at the cavity bottom. " The purification of phosphate substituted calixarenes has been studied by chiral HPLC and by normal reverse phase HPLC. Mono(6-0-diphenoxyphosphoryl)-P-cyclodextrin (9) and mono(6-0-ethoxyhydroxyphosphoryl)-p-cyclodextrin (10) have been synthesised and show enantioselective inclusion of D and L amino acids e.g. 3.6 for D/L serine in the case of 9). ... 

Lipase (PsL)-mediated acylation reaction of a-methyl benzyl alcohol by vinyl acetate (Scheme 10.5) gives high enantioselectivity (E value 200) in [BMIM][Tf2N] than in methyl t r-butyl ether (MTBE) (E=4) at 55°C. At the boiling point of vinyl acetate, the E value was reduced to 150 from 200 [86, 87]. Similarly, lipase from Pseudomonas fluorescens (Lipase AK)-catalyzed enantioselective acylation of phosphate substituted primary alcohols in [BMIM][PF ] with enantioselectivity comparable to DIPE, though no selectivity was obtained in [BMIM][BF ] [87]. 

---