Disease relevance of isoprene

• Convergence of isoprene and polyketide biosynthetic machinery: isoprenyl-S-carrier proteins in the pksX pathway of Bacillus subtilis [1].
• Non-neoplastic lesions in mice exposed to isoprene included spinal cord degeneration, testicular atrophy, degeneration of the olfactory epithelium, and epithelial hyperplasia of the forestomach [2].
• Geraniol, an acyclic end product of a plant isoprene pathway and a pyrophosphorylated intermediate in plant and animal pathways, caused a concentration-dependent increase in the population doubling time of murine P388 leukemia cells in suspension culture and of B16 melanoma cells in monolayer culture [3].
• To test the effect of isoprene tail length, N2 and clk-1 animals were fed E. coli engineered to produce Q7, Q8, Q9, or Q10 [4].
• Acute respiratory distress syndrome (ARDS) patients had lower isoprene concentration differences than patients without ARDS [5].

Psychiatry related information on isoprene

• Our results confirm recent observations of a diurnal level variation associated with sleep or wakefulness; a new finding is that young children have much lower levels of isoprene in breath than adults [6].
• Here we report the effects of variation of reaction time, relative humidity and initial ozone concentration on irritant formation in a flow reaction system using R-(+)-limonene and isoprene [7].

High impact information on isoprene

• Exposure to increased CO2 significantly reduced the cellular content of dimethylallyl diphosphate, the substrate for isoprene synthesis, in both leaves and leaf protoplasts [8].
• Our results highlight the potential for uncoupling isoprene emission from biomass accumulation in an agriforest species, and show that negative air-quality effects of proliferating agriforests may be offset by increases in CO2 [8].
• The inhibitory activity of GDI derives both from an ability to bind the carboxy-terminal isoprene of Rho family members and extract them from membranes, and from inhibition of GTPase cycling between the GTP- and GDP-bound states [9].
• From our data it can be concluded that isoprenylation of lamins in the nucleus, as it is observed under certain conditions of isoprene starvation, represents a default pathway rather than the physiological situation [10].
• The thermoprotection hypothesis suggests that isoprene protects thylakoids from damage at high temperatures [11].

Chemical compound and disease context of isoprene

• Diphenylamine (DPA), a known inhibitor of polyene and isoprene biosynthesis, is shown to inhibit flash-activatable electron transfer in photosynthetic membranes of Rhodobacter capsulatus [12].
• Purification of a glutathione S-transferase and a glutathione conjugate-specific dehydrogenase involved in isoprene metabolism in Rhodococcus sp. strain AD45 [13].
• Measurement of the VOC emission pattern from a pure culture of Lactococcus lactis confirmed the positive correlations for the protonated masses 89 (tentatively identified as butyric acid), 63 (tentatively identified as dimethylsulfide), 69 (likely isoprene) and 73 (likely butanone) [14].
• Here, we demonstrate that the isoprene-producing bacterium, Bacillus subtilis, contains an isoprene synthase activity that catalyzes dimethylallyl diphosphate-dependent isoprene formation [15].
• This study was designed to assess breath alkanes in a group of patients with active inflammatory bowel disease by a technique that clearly distinguishes pentane from isoprene, to prevent overestimation of values as in previous studies [16].

Biological context of isoprene

• Identification and characterization of three novel missense mutations in mevalonate kinase cDNA causing mevalonic aciduria, a disorder of isoprene biosynthesis [17].
• Isoprene, an endogenous hydrocarbon and industrial chemical, induces multiple organ neoplasia in rodents after 26 weeks of inhalation exposure [2].
• In this study, we developed a variety of substrates and inhibitors of Icmt that vary in the isoprene moiety in order to gain information about the nature of the lipophilic substrate binding site [18].
• Although the hydrogenation of the isoprene double bond and the conjugated fatty acid both use NADH as the primary reductant, the two reactions appear to be catalyzed by different enzymes [19].
• Alternatively, a compound produced as an intermediate in leucine breakdown to HMG-CoA (e.g. dimethylcrotonyl-CoA) could be directly reduced to produce an isoprene alcohol followed by phosphorylation to enter the isoprenoid pathway post-MVA [20].

Anatomical context of isoprene

• Two isoprenoids with 9 to 10 isoprene chains (polyprenoids), N-(p-methylbenzyl)decaprenylamine and N-solanesyl-N,N'-bis(3,4-dimethoxybenzyl)ethylenediamine overcame the multidrug resistance almost completely in cultured Chr-24, whereas they only slightly sensitized the parental KB cells to anticancer agents [21].
• When H-Ras, N-Ras, K-Ras4A, and K-Ras4B were expressed individually in COS cells, H-Ras prenylation and membrane association were found to be uniquely sensitive to farnesyl transferase inhibitors; N- and K-Ras proteins incorporated the geranylgeranyl isoprene group and remained associated with the membrane fraction [22].
• Endothelial degeneration in the CNS and optic nerve may have reflected in vitro morphologic effects of HMG CoA reductase inhibitors due to extreme inhibition of nonsterol isoprene synthesis [23].
• Both K-ras and H-ras protooncogene mutations are associated with Harderian gland tumorigenesis in B6C3F1 mice exposed to isoprene for 26 weeks [24].
• Since bisphosphonates are known to be potent, nanomolar inhibitors of the mevalonate/isoprene pathway enzyme farnesyl pyrophosphate synthase (FPPS), we also compared the pharmacophores for gammadelta T cell activation with those for FPPS inhibition, using the Catalyst program [25].

Associations of isoprene with other chemical compounds

• Saccharomyces cerevisiae strains that contain the ery8-1 mutation are temperature sensitive for growth due to a defect in phosphomevalonate kinase, an enzyme of isoprene and ergosterol biosynthesis [26].
• Most of the toxic and carcinogenic effects caused by isoprene, as well as the species' difference in response, had been observed after inhalation exposures to 1,3-butadiene [2].
• Mevalonic aciduria is the first proposed inherited disorder of the cholesterol/isoprene biosynthetic pathway in humans, and it is presumed to be caused by a mutation in the gene coding for mevalonate kinase [27].
• In the current study, inhibitors of the isoprene biosynthetic pathway were used to define further this mevalonic acid derivative involved in the accelerated degradation of HMG-CoA reductase [28].
• It is proposed that the synthesis of dolichol and dolichyl-P do not share the same terminal steps; saturation and terminal isoprene condensation occur in cooperation; and substrate concentration and pH influence the terminal enzyme(s) and the nature of the final product in the polyprenol biosynthesis [29].

Gene context of isoprene

• Both isoprene monoepoxides were oxidized by CYP2E1 to the diepoxide at similar enzymatic rates [30].
• The products of the Rer2 and Srt1 proteins consist of 14-17 and 18-23 isoprene units, respectively [31].
• Thus, differences in epoxide hydrolase activity between species may be of crucial importance for the toxicity of isoprene in the various species [30].
• All-trans-polyprenyl diphosphates containing 3-13 isoprene units are synthesized, which identifies the B318L protein as a trans-prenyltransferase [32].
• Our data demonstrate that RhoB-F and RhoB-GG which differ only by a 5-carbon isoprene behave differently in rodent cells highlighting the important role of prenyl groups in protein function and emphasize the potency of RhoB to regulate negatively the oncogenic signal [33].

Analytical, diagnostic and therapeutic context of isoprene

• Molecular cloning and sequence of a cholesterol-repressible enzyme related to prenyltransferase in the isoprene biosynthetic pathway [34].
• The distribution of chain lengths of the labeled polyisoprenols of F2A8, B4-2-1, and wild-type cells was the same as determined by high pressure liquid chromatography using a reverse-phase column, with the predominant chain length being 19 isoprene units [35].
• In contrast to this limited addition of IPP to DMAPP, we measured 7000 additions of isoprene per rubber molecule in a previous titration of active allylic ends of rubber molecules by purified prenyltransferase (Light, D. R., and Dennis, M. S. (1989) J. Biol. Chem. 264, 18589-18597) [36].
• Estimates of chain length by thin layer chromatography indicate that the lipid has 11 to 12 isoprene identity as a C55-60-polyisoprenyl pyrophospho-N-acetylglucosamine [37].
• Two subjects with LA had inexplicable, positive, nonreproducible intradermal skin test reactions to solutions from vials containing bromobutyl but not vials with isoprene synthetic closures [38].

References