Di- phosphate

IPP and its DMAPP structural isomer are produced from glycolytic products by the methyl erythritol phosphate (MEP) pathway (Figure 5.3.1, Pathway 1). These isoprene units are condensed in a stepwise fashion to form the precursor to all carotenoids, geranylgeranyl di-phosphate (GGPP). GGPP is not solely metabolized to make carotenoids, but is a precursor for many other primary and secondary metab-... 

This enzyme [EC 2.5.1.10], also known as farnesyl-di-phosphate synthase, catalyzes the reaction of geranyl diphosphate with isopentenyl diphosphate to produce trans,trans-farnesyl diphosphate and pyrophosphate (or, diphosphate). Some forms of this enzyme will also utilize dimethylallyl diphosphate as a substrate. However, the enzyme will not accept larger prenyl diphosphates as an efficient substitute for geranyl diphosphate. 

Solutions of alkali trimetaphosphates are practically stable under neutral conditions and at 20°C or below. At a lower pH they are hydrolyzed according to a first order law and transformed via tri- and di-phosphates to monophosphates (10, S3, 51, ISO, 238, 244, 393). 

Pyro- and di-phosphates, the simplest members of the group of condensed phosphates, are so well known that only the results of recent investigations will be described here, and only in so far as they bear on the chemistry of condensed phosphates. Thus, ever since Clark s investigations 52), it has been common knowledge among chemists that diphosphates arc obtained by heating monohydrogen phosphates, or by double decomposition of other diphosphates. It was unexpected, however, to find that an equilibrium... 

In the system (KII2P04—H3P04) high-molecular potassium polyphosphates are formed on heating, together with acid mono- and di-phosphate but only a little oligophosphate (363). But tertiary P04 tetrahedra occur not only in phosphates with Na P < 1. They can also be detected in Graham s and Kurrol s salt with Mr P = 1 (224, 284, 85, 86) and are also formed in melts of anhydrous trimetaphosphates, especially in a dry atmosphere (364). Their equilibrium concentration in the melt is about 2%. 

A glycerol phosphate polymer containing 1,3-linkages could be hydrolyzed in alkali by fission at either side of each phosphodiester linkage, to give glycerol and its mono- and di-phosphates in proportions which would... 

To obtain model compounds for the study of inositol phosphates, Kil-gour and Ballou180 treated di-O-isopropylidenepinitol (LXIV) and di-O-isopropylidene-Zeyo-inositol (XXVIII) with diphenyl phosphorochloridate. For the latter, the result was surprising instead of the expected mono-or di-phosphate, a cyclic phosphate (LXXIX) was obtained. In it, the phosphate group is attached to two irans-hydroxyl groups, like the third iso-propylidene group in tri-O-isopropylidene-fevo-inositol (see p. 149). This... 

To avoid dissolution or extraction of the FR, FR oligomer can be used instead of monomer. Using this approach, Ma et al.39 reported the synthesis of phosphate-polyester copolymers from spirocyclic pentaerythritol di(phosphate acid monochloride)s. It was shown that LOI of the copolymer increases with increasing phosphate content to reach a maximum of 30 vol %. 

If the body cells require instant energy (as in exercise), the glucose is supplied with oxygen from the blood and is immediately oxidized on the instructions of a facilitating ADP (adenosine di-phosphate) molecule to release energy ... 

Sugar phosphates, mainly the hexose mono- and di-phosphates, play an important part in alcoholic fermentation. The calcium salts of these esters have been prepared. 

Note that the muscular motive power of the human body (see the introduction to this book) comes from the isothermal hydrolysis of adenosine tri-phosphate to di-phosphate (Atkins, 1995), a wet reaction in which little power is associated with reactant and product handling. Nature has evolved to a position of elegant fuel economy. Nature also has to undertake a complex chemical manufacturing task to provide automated selfmaintenance of the body. Chemical reactions are isothermal at blood temperature, along the same lines as the Regenesys system of Chapter 2. 

FIGURE 9.98 Events taking place in the plasma membrane on stimulation of a cell. Phospha tidylinositol (Pi) and more hi ly phosphoiylated versions of this lipid account for 2 to 8% of the lipids of the plasma membrane of eukaryotic cdIs. The inositol 1,4,5 triphosphate (fP3) moiety of phosphatidyl inositol- 4,8-di phosphate may be hydiulyitec from this lipid immediately after the cell is stimulated. For example, the stimulation of platelets by thrombin or the islets of the pancreas by glucose is followed by the release of 1P3 into the cytoplasm. In some cells, arachidonic acid is hydrolyzed from l-acyl-2-arachidonyl-glyceroL which can Support a burst of prostaglandin. synthesis. 

Eschenmoser and co-workers [35] studied the aldomerization of glycoaldehyde phosphate which led to mixtures containing mostly racemates of the two diastereomeric tetrose 2,4-di-phosphate and eight hexose 2,4,6-triphosphates (O Scheme 2, route A). At 20 °C in the absence of air, a 0.08-molar solution of glycolaldehyde phosphate 2 in 2-M NaOH gave 80% yield of a 1 10 mixture of tetrose 3 and hexose 4 derivatives with DL-allose 2,4,6-triphosphate comprising up to 50% of the mixture of sugar phosphate [36]. 

Nucleoside 2 (or 3 ),5 -diphosphates have been isolated by degradation of certain coenzymes, as well as from hydrolyzates of nucleic acids. Adenosine 3, 5 -diphosphate (see p. 320) has been isolated by enzymic hydrolysis of coenzyme A and from active sulfate (adenosine 3 -phosphate 5 -phosphosulfate). Adenosine 2, 5 -diphosphate was shown to be present in the adenylic acid moiety of the coenzyme adenine-nicotinamide dinucleotide phosphate which, by treatment with a 5 -nucleotidase from potatoes, is converted into adenosine 2 -phosphate. Adenosine 3, 5 -di-phosphate is reported to play a role as a cofactor in the bioluminescence of Renilla reniformis (pansy) Ribonucleic acid carrying a terminal 5 -phos-phate group yields ribonucleoside 3, 5 -diphosphates on digestion with phosphoesterases. ... 

Harden and Young, J. Ch. Soc. (1908) Abs. i, 590 were the first to show that the addition of phosphates (disodium phosphate) to a mixture of yeast juice and dextrose resulted in both an initial acceleration and in an increased total fermentation. They also showed that there was an optimum concentration of phosphate, deviations from which in either direction resulted in a diminished rate of fermentation. It is assumed that a hexose-di-phosphate is formed as follows ... 

It has been found by further investigation that there is apparently another step in the fermentation reaction in which the dextrose di-phosphate splits into two moles of triose mono-phosphate. It should be particularly noted that the immediately preceding study of the mechanism of the action of yeast juice is not directly applicable to the action of yeast. E.gSlator (loc. cit.) found that phosphates are without accelerating effect when living yeast cells are employed. 

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