Synthesis isoprene

Isoprene synthesis in isolated embryonic Drosophila cells sterol independent eukaryotic cells. J. Biol. Chem. 258, 8503-8511. 

HMG-CoA reductase is the major regulatory enzyme in cholesterol biosynthesis. HMG-CoA reductase is controlled hormonally by insulin and glucagon and transcription and translation of the enzyme can be suppressed by the presence of cholesterol in cells. Mevalonate is converted in the cytosol to the five carbon building blocks of isoprene synthesis-isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DPP)-in the reactions shown in Figure 19.19. Subsequently, IPP and DPP form famesyl pyrophosphate in the cytosol (Figure 19.20)... 

The continuous increase of isoprene demand has determined the enhancement of researches focused on the elaboraticxi of new and efficient routes for the industrial synthesis of this valuable diene. The acid-catalyzed cc ensation of formaldehyde and isobutene, known as Prins reacticxi, is already a recognized industrial route for the isoprene synthesis, being applied as two-stages process, condensation to form 4,4-dimethyl-l,3-dioxane in the presence of an aqueous sulphuric acid and its decomposition to isoprene using solid phosphoric acid catalysts. 

PIS Pispas, S. and Hadjichristidis, N., End-functionahzed block copolymers of styrene and isoprene Synthesis and association behavior in dilute solution. Macromolecules, 27, 1891, 1994. 

But as IE is also in close reverse dependence on partial pressure of CO2 in the air (rises with the decrease in partial pressure) /7, 12/ which mesns that isoprene synthesis in which acetyl CoA of chloroplast origin is used is obviously mediated by the connection with the reaction of photosynthetic carboxylation. 

The mevalonic acid molecule (1) possesses a chiral center (bearing hydroxyl and methyl) at C-3. Only the (3/ )-enanti-omer is used in isoprene synthesis. The fate of each of the six possible (3/ )-monotritiated species of MVA has been determined in subsequent reactions of this important precursor. These reactions are highly stereospecific (Cori, 1983 Mann, 1987). 

Vickers, C.E., Possell, M., Cojocariu, C.I., Velikova, V.B., Laothawornkitkul, J., Ryan, A., Mullineaux, P.M., Hewitt, C.N. (2009) Isoprene synthesis protects transgenic tobacco plants from oxidative stress. Plant, Cell Environment, 32, 520-531. 

The Prins reaction is a known method of 0-containing heterocycles formation [1, 2], In some cases the insufficient selectivity of this reaction is a drawback. For instance, the first stage of the isoprene synthesis by the dioxane method [3] is accompanied by the formation of a large number of methyldihydropyrans [4-6]. So, investigation and specification of mechanism of Prins reaction can solve this problem. 

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