- Monoterpene biosynthesis in the liverwort conocephalum conicum: demonstration of sabinene synthase and bornyl diphosphate synthase in honour of professor G. H. Neil towers 75th birthday
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(-)-Sabinene is the major monoterpene produced by a European strain of the liverwort Conocephalum conicum. A cell-free extract from in vitro cultured plants catalysed the cyclization of geranyl diphosphate to sabinene. The responsible monoterpene cyclase was partially purified and characterized as an operationally soluble enzyme of Mr, 65000, with a pH optimum at 7.5 and a requirement for a divalent metal ion as the only cofactor, with Mg2+ preferred. The general properties of the sabinene synthase from C. conicum resemble those of other monoterpene cyclases from gymnosperms and angiosperms. A North American strain of the liverwort produces (+)-bornyl acetate as the major monoterpene and it was demonstrated that bornane-type monoterpenes are derived from geranyl diphosphate in this liverwort, as in higher plants, by the action of bornyl diphosphate synthase.
- Adam, Klaus-Peter,Crotea, Rodney
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- Acorenone B: AChE and BChE inhibitor as a major compound of the essential oil distilled from the ecuadorian species niphogeton dissecta (Benth.) J.F. macbr
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This study investigated the chemical composition, physical proprieties, biological activity, and enantiomeric analysis of the essential oil from the aerial parts of Niphogeton dissecta (culantrillo del cerro) from Ecuador, obtained by steam distillation. The qualitative and quantitative analysis of the essential oil was realized by gas chromatographic and spectroscopic techniques (GC-MS and GC-FID). Acorenone B was identified by GC-MS and NMR experiments. The enantiomeric distribution of some constituents has been assessed by enantio-GC through the use of a chiral cyclodextrin-based capillary column. We identified 41 components that accounted for 96.46% of the total analyzed, the major components were acorenone B (41.01%) and (E)-β-ocimene (29.64%). The enantiomeric ratio of (+)/(-)-β-pinene was 86.9:13.1, while the one of (+)/(-)-sabinene was 80.9:19.1. The essential oil showed a weak inhibitory activity, expressed as Minimal Inhibitory Concentration (MIC), against Enterococcus faecalis (MIC 10 mg/mL) and Staphylococcus aureus (MIC 5 mg/mL). Furthermore, it inhibited butyrylcholinesterase with an IC50 value of 11.5 μg/mL. Pure acorenone B showed inhibitory activity against both acetylcholinesterase and butyrylcholinesterase, with IC50 values of 40.8 μg/mL and 10.9 μg/mL, respectively.
- Calva, James,Bec, Nicole,Gilardoni, Gianluca,Larroque, Christian,Cartuche, Luis,Bicchi, Carlo,Montesinos, José Vinicio
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- Converting S-limonene synthase to pinene or phellandrene synthases reveals the plasticity of the active site
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S-limonene synthase is a model monoterpene synthase that cyclizes geranyl pyrophosphate (GPP) to form S-limonene. It is a relatively specific enzyme as the majority of its products are composed of limonene. In this study, we converted it to pinene or phellandrene synthases after introducing N345A/L423A/S454A or N345I mutations. Further studies on N345 suggest the polarity of this residue plays a critical role in limonene production by stabilizing the terpinyl cation intermediate. If it is mutated to a non-polar residue, further cyclization or hydride shifts occurs so the carbocation migrates towards the pyrophosphate, leading to the production of pinene or phellandrene. On the other hand, mutant enzymes that still possess a polar residue at this position produce limonene as the major product. N345 is not the only polar residue that may stabilize the terpinyl cation because it is not strictly conserved among limonene synthases across species and there are also several other polar residues in this area. These residues could form a “polar pocket” that may collectively play this stabilizing role. Our study provides important insights into the catalytic mechanism of limonene synthases. Furthermore, it also has wider implications on the evolution of terpene synthases.
- Xu, Jinkun,Ai, Ying,Wang, Jianhui,Xu, Jingwei,Zhang, Yongkang,Yang, Dong
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- Transcriptome profiling, and cloning and characterization of the main monoterpene synthases of Coriandrum sativum L.
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Terpenoids are a large and diverse class of specialized metabolites that are essential for the growth and development of plants, and have tremendous industrial applications. The mericarps of Coriandrum sativum L. (coriander) produce an essential oil (EO) rich in monoterpenes, volatile C10 terpenoids. To investigate EO metabolism, the transcriptome of coriander mericarps, at three developmental stages (early, mid, late) was sequenced via Illumina technology and a transcript library was produced. To validate the usability of the transcriptome sequences, two terpene synthase candidate genes, CsγTRPS and CsLINS, encoding 558 and 562 amino acid proteins were expressed in bacteria, and the recombinant proteins purified by Ni-NTA affinity chromatography. The 65.16 (CsγTRPS) and 65.91 (CsLINS) kDa recombinant proteins catalyzed the conversion of geranyl diphosphate, the precursor to monoterpenes, to γ-terpinene and (S)-linalool, respectively, with apparent Vmax and Km values of 2.24 ± 0.16 (CsγTRPS); 19.63 ± 1.05 (CsLINS) pkat/mg and 66.25 ± 13 (CsγTRPS); 2.5 ± 0.6 (CsLINS) μM, respectively. Together, CsγTRPS and CsLINS account for the majority of EO constituents in coriander mericarps. Investigation of the coriander transcriptome, and knowledge gained from these experiments will facilitate future studies concerning essential and fatty acid oil production in coriander. They also enable efforts to improve the coriander oils through metabolic engineering or plant breeding.
- Galata, Mariana,Sarker, Lukman S.,Mahmoud, Soheil S.
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- Isotope sensitive branching and kinetic isotope effects to analyse multiproduct terpenoid synthases from Zea mays
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Multiproduct terpene synthases TPS4-B73 and TPS5-Delprim from Zea mays exhibit isotopically sensitive branching in the formation of mono- and sesquiterpene volatiles. The impact of the kinetic isotope effects and the stabilization of the reactive intermediates by hyperconjugation along with the shift of products from alkenes to alcohols are discussed.
- Gatto, Nathalie,Vattekkatte, Abith,K?llner, Tobias,Degenhardt, J?rg,Gershenzon, Jonathan,Boland, Wilhelm
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supporting information
p. 3797 - 3800
(2015/03/30)
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- Monoterpene synthase activities in leaves of Picea abies (L.) Karst. and Quercus ilex L.
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In addition to direct ecological functions in the interaction of plants with the environment, the emission of monoterpenes, especially from the foliage of evergreen trees, is of great importance for the production of ozone and photochemical oxidants in the troposphere. In the present work, we established a reproducible non-radioactive standard enzyme assay and characterized monoterpene synthase activities in needles of Norway spruce (Picea abies (L.) Karst.) and in leaves of holm oak (Quercus ilex L.). In Norway spruce, the dominant monoterpenes formed were α-pinene, camphene, and to a lesser extent β-pinene and limonene. In holm oak, α-pinene, sabinene, and β-pinene were the main products, while limonene was a minor component. Under optimum conditions, in both Norway spruce and holm oak, monoterpene formation remained constant up to 180 min and 90 min, respectively, and varied with the buffer and Mg2+ and Mn2+ concentrations used. Optimum temperature for monoterpene synthase activity was 40°C in both species; optimal pH ranged between 6.5 and 7.5 in both species. Apparent Michaelis- constants for the substrate GDP were ca. 17.9 ± 5.1 μM for Norway spruce and ca. 69.4 ± 22.1 μM for holm oak. Molecular weight determination by FPLC indicated that the monoterpene synthases in Norway spruce and holm oak have native molecular weights of ca. 59 and 50 kDa, respectively. (C) 2000 Elsevier Science Ltd.
- Fischbach, Robert J.,Zimmer, Ina,Steinbrecher, Rainer,Pfichner, Andreas,Schnitzler, Joerg-Peter
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p. 257 - 265
(2007/10/03)
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