Diphosphate esters

N-Acetyl-Dgalactosamine uridine diphosphate ester of uridine diphosphate ester of... 

Previous methods for the preparation of salts of geranyl diphosphate and other allylic isoprenoid diphosphates are based on condensation between the alcohol and inorganic phosphate by trichloroacetonitrile as originally reported by Cramer and modified by Popjak The reaction generates a complex mixture of organic and inorganic polyphosphates which must be separated by chromatography. The desired diphosphate ester has been prepared on small... 

The direct displacement reaction can be used to prepare many of the common diphosphate esters in the isoprene biosynthetic pathway, Including isopentenyl diphosphate The yields are typically 60-90% from the... 

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. 

A detailed analysis of solid-state structures of several unrelated systems that catalyze the hydrolysis of diphosphate esters (alkaline phosphatase and the Klenow fragment , among others) revealed that their active sites invariably contain conserved carboxylate... 

The diphosphate ester, TPP, is the physiologically active vitamer and functions as a coenzyme (67,68). The absorption, metabolism, and physiological functions of thiamine have recently been reviewed (20,67,68). 

The importance of magnesium ions for the catalytic activity of the yeast PDC was recognized in 1931 by Lohmann and Schuster [30]. One year later, Auhagen [31] isolated a further thermostable substance, cocarboxylase , which was necessary for the decarboxylation of pyruvate. In 1937, Lohmann and Schuster [32] investigated the constitution of cocarboxylase and found it to be a diphosphate ester of vitamin B1 (ThDP) 3 (Scheme 2). Three years later, Green and co-workers [33] proposed that magnesium functions as a bridge ... 

The uridine diphosphate ester derivatives in a non-capsulated. Type II pneumococcus and a capsulated. Type III pneumococcus were investigated by Smith, Mills, and Harper." The capsule of the Type III pneumococcus is composed of a polysaccharide having 4-0-( 8-D-glucopyranosyluronic acid)-D-glucose as a repeating unit. n-Glucuronic acid, D-glucose, and L-rhamnose are constituents of the capsular polysaccharide of the Type II pneumococcus. 

Figure 5.7 Proposed mechanism for the cyclization of geranylgeranyl diphosphate (GGPP) to the diterpene copalyl diphosphate, an example of terpene synthase-catalysed cyclization initiated by double-bond protonation, rather than by hydrolysis of the diphosphate ester. PP indicates a diphosphate moiety.

A uridine pyrophosphate derivative of Ai -acetyl-n-glucosamine which contains an extra phosphate group has been isolated from a hot-water extract of hen oviducts. Uridine 5-phosphate and uridine 5-pyrophosphate have been recovered from acid hydrolyzates of this compound. A diphosphate ester of A-acetyl-n-glucosamine can also be obtained from acid hydrolyzates of this uridine compound. Because of the catalytic activity of phospho-A -acetyl-n-glucosamine mutase toward it, it is probably AT-ace-tyl-D-glucosamine 1,6-diphosphate. 

The pathway by which the 3, 5 -diphosphate esters of thymidine and 2 -deoxycytidine are formed during acid hydrolysis of 2 -deoxyribonucleic acid is shown in Scheme 27 " Cleavage of the glycosylic linkages to the... 

Replacement of OH with NH2 has been attempted in a stepwise fashion via the A,C-dihydroxy compound 95b, but treatment with NO2BF4 results in oxidation (see Section 5.3.2) rather than nitration. A more successful approach involves treatment of the diphosphate ester 168 (Y = OPO(OEt)2 = OH) with KNH2 in NH3, which gives a mixture from which the monoamine 168b and diamine 168c can be isolated in 44% and 8% yield, respectively. Still... 

Tritolyl phosphate (TTP) has been examined as a pretreatment for E-glass in epoxide laminates and thermoplastic adhesives for bonding poly(vinyl chloride) to aluminum, steel to zinc, and acrylonitrile butadiene styrene to aluminum [59]. Mono- and diphosphate esters have been claimed to be suitable adhesion-promoting primers for acrylic adhesives on metal [60,61], unsaturated acid phosphates have been suggested as primers for use on metals to be bonded with free radical initiated adhesives [42], and thiopho-sphate esters have been suggested for adhesives to be used on plastics, ceramics, and metals [62]. 

McKenna reported the efiicient synthesis of the alpha, P-difluoromethylene deoxynucleoside 5 -triphosphate of adenosine and cytosine (89a,b), obtained enzymatically from catalytic ATP, phosphoenol pyruvate, nucleoside diphosphate kinase and pyruvate kinase using the nucleoside difluor-omethylene bisphosphonates as substrate for the kinase. The bispho-sphonate was prepared by nucleophilic displacement of the 5 -0-tosyl nucleoside precursor with tris(tetrabutylammonium) difluoromethylenebi-sphosphonate. Finally Mackman synthesised the diphosphate esters of two cyclopentyl based nucleoside phosphonates (90a,b). While (90b) was unstable following reduction of (90a) and therefore unsuitable for biological evaluation, (90a) exhibited potent inhibition against HIV reverse transcriptase. ... 

Isopentenyl diphosphate and dimethylallyl diphosphate are structurally similar—both contain a double bond and a diphosphate ester unit—but the chemical reactivity expressed by each is different. The principal site of reaction in dimethylallyl diphosphate is the carbon that bears the diphosphate group. Diphosphate is a reasonably good leaving group in nucleophilic substitution reactions, especially when, as in dimethylallyl diphosphate, it is located at an allylic carbon. Isopentenyl diphosphate, on the other hand, does not have its leaving group attached to an allylic carbon and is far less reactive than dimethylallyl diphosphate toward nucleophilic reagents. The principal site of reaction in isopentenyl diphosphate is the carbon-carbon double bond, which, like the double bonds of simple alkenes, is reactive toward electrophiles. 

The enzyme-catalyzed reactions that lead to geraniol and farnesol (as their diphosphate esters) are mechanistically related to the acid-catalyzed dimerization of alkenes discussed in Section 6.21. The reaction of an ally lie diphosphate or a carbocation with a source of 7T electrons is a recurring theme in terpene biosynthesis and is invoked to explain the origin of more complicated structural types. Consider, for example, the formation of cyclic monoterpenes. Neryl diphosphate, formed by an enzyme-catalyzed isomerization of the E double bond in geranyl diphosphate, has the proper geometry to form a six-membered ring via intramolecular attack of the double bond on the allylic diphosphate unit. 

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