Prenyl pyrophosphates

Isopentenyl diphosphate (prenyl pyrophosphate) 527, 689, 690s, 712s Isopentenyladenosine 234s Isopeptidases 525 Isopeptide linkage in proteins 80 to ubiquitin 524... 

The or/Ao-prenylphenol substructure is the initial product of the biogenetic prenyl-pyrophosphate-phenol coupling. Many modifications of this structure are observed in nature. The electroreductive ring opening of 3-pheny lthiochroman 86 in an MeCN— Et4NBr—(Hg) system provides l-isopent-2-enyl-2-naphthol 87 in 53% yield (Scheme 3-32)79). 

Morita, C. T., Beckman, E. M., Bukowski, J. F., Tanaka, Y, Band, H., and Bloom, B. R. et al. (1995). Direct presentation of nonpeptide prenyl pyrophosphate antigens to human gamma delta T cells. Immunity 3(4), 495-507. 

Reiss, Y., Brown, M.S., and Goldstein, J.L. (1992). Divalent cation and prenyl pyrophosphate specificities of the protein farnesyltransferase from rat brain, a zinc metalloenzyme. J Biol Chem 267 6403-6408. 

Yokoyama, K., Zimmerman, K., Scholten, J., and Gelb, M.H. (1997). Differential prenyl pyrophosphate binding to mammalian protein geranylgeranyltransferase-I and protein farnesyltransferase and its consequence on the specificity of protein prenylation. J Biol Chem 272 3944-3952. 

Several papers report new findings on ubiquinone biosynthesis. A mitochondrial membrane-rich preparation from baker s yeast can convert 4-hydroxybenzoate and isopentenyl pyrophosphate into the ubiquinone precursor 3-all-trans-hexaprenyl-4-hydroxybenzoate (234). Details of the cell-free system are presented. With preformed polyprenyl pyrophosphates, the system catalysed the polyprenylation of several aromatic compounds, e.g. methyl 4-hydroxybenzoate, 4-hydroxybenzaldehyde, 4-hydroxybenzyl alcohol, and 4-hydroxycinnamate. No evidence was obtained for the involvement of 4-hydr-oxybenzoyl-CoA or 4-hydroxybenzoyl-S-protein in the reaction. With shorter-chain prenyl pyrophosphates a shorter prenyl side-chain was introduced, e.g. geranyl and farnesyl pyrophosphates gave products with a 3-diprenyl and 3-triprenyl side-chain respectively. A crude enzyme preparation from E. coli... 

Reaction involving the formation of a sulfonium intermediate (80) followed by a sigmatropic rearrangement was formulated by Trost and Biddlecom (Scheme 8) and cyclization initiated by an allylic copper carbenoid (81) was proposed by Cohen and coworkers (Scheme 9). The common feature of all of these proposed mechanisms relies on the electrophilic addition of the donor to the acceptor prenyl pyrophosphate and is... 

Identification and quantitative analyses of 25 compounds in steam distillates of burley tobacco stalk were accomplished. Compounds included twelve C,-C. compounds that were probable fatty acid oxidation products and 13 compounds >C that varied in origin. The latter included oxidation products of fatty acids, a C. prenyl pyrophosphate metabolite, and biodegradation products of carotenoids and chlorophyll. About 1/3 of the distillate mass was accounted for. Burley tobacco stalk headspace volatiles were also studied. When compared to the steam distillate, the headspace contained greater concentrations of sesquiterpenoids but lower concentrations of C, and C aldehydes and alcohols. Volatiles in steam distillates of tobacco stalk were not quantitatively different in a fungal resistant and a fungal sensitive variety of tobacco. Yield comparisons were made of headspace volatiles from tobacco and wheat. 

Isopentenyl pyrophosphate is produced from glucose and can be isomerised to prenyl pyrophosphate. 

The double bond of isopentenyl pyrophosphate can be isomerised into the thermodynamically more favourable trisubstituted position by manganese ions, giving prenyl pyrophosphate (2.11). The reverse isomerisation can be achieved by magnesium ions. Both isomerisations are, of course, directed by enzymes. 

In bacteria and plastids of plants, formation of prenyl pyrophosphates, which are the precursors of carotenoids, proceeds via an alternative—the glyceraldehyde-3-phosphate pyruvate pathway. The pathway is apparently the sole source of isoprenoid compounds for the unicellular algae Scenedesmus (Metzler 2003). Initially, pyruvate is decarboxylated by a l-deoxyxylulose-5-phosphate synthase and condensed with D-glyceraldehyde 3-phosphate to form 1-deoxyxylulose 5-phosphate. This product may be the branching point for independent routes to isopentyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP). 

A problem in the use of dimethylallyl pyrophosphate (3) is its instability. In a study of this problem the half-life of this substance was examined over a range of pH values and temperatures. Both cis- and trans-prenyl pyrophosphates (4 n = 0, 1, or 2) occur in Pinus radiata. Their biosynthesis from [2- C,3R,4K- H]-mevalonic acid proceeded with retention of tritium whereas with [2- C,3K,4S- HJmevalonic acid tritium was lost [except in the case of isopentenyl pyrophosphate (4 n = 0)]. The authors suggest that since they could not detect an isomerase, there may be a cis- and a trans-prenyl transferase both of which eliminate the label derived from [4S- H]mevalonic acid. However, compart-mentalization may have resulted in the isomerase not being available to the administered monoterpenoids, although it may act on geranyl pyrophosphate formed in situ. The absence of 6-cis-famesol derivatives tends to support this idea. Further work on this system again produced no evidence for isomerization or metabolism of [l- H]nerol pyrophosphate to 2-rrans-6-c(s-farnesyl pyrophosphate. 

---