| 1. |
- Olsson, Mikael E., et al.
(författare)
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Localization of enzymes of artemisinin biosynthesis to the apical cells of glandular secretory trichomes of Artemisia annua L
- 2009
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Ingår i: Phytochemistry. - : Elsevier BV. - 0031-9422 .- 1873-3700. ; 70:9, s. 1123-1128
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Tidskriftsartikel (refereegranskat)abstract
- A method based on the laser microdissection pressure catapulting technique has been developed for isolation of whole intact cells. Using a modified tissue preparation method, one outer pair of apical cells and two pairs of sub-apical, chloroplast-containing cells, were isolated from glandular secretory trichomes of Artemisia annua. A. annua is the source of the widely used antimalarial drug artemisinin. The biosynthesis of artemisinin has been proposed to be located to the glandular trichomes. The first committed steps in the conversion of FPP to artemisinin are conducted by amorpha-4,11-diene synthase, amorpha-4,11-diene hydroxylase, a cytochrome P450 monooxygenase (CYP71AV1) and artemisinic aldehyde Delta 11(13) reductase. The expression of the three biosynthetic enzymes in the different cell types has been studied. In addition, the expression of farnesyldiphosphate synthase producing the precursor of artemisinin has been investigated. Our experiments showed expression of farnesyldiphosphate synthase in apical and sub-apical cells as well as in mesophyl cells while the three enzymes involved in artemisinin biosynthesis were expressed only in the apical cells. Elongation factor 1 alpha was used as control and it was expressed in all cell types. We conclude that artemisinin biosynthesis is taking place in the two outer apical cells while the two pairs of chloroplast-containing cells have other functions in the overall metabolism of glandular trichomes.
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| 2. |
- Teixeira, M.C., et al.
(författare)
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Molecular cloning and expression analysis of three omega-6 desaturase genes from purslane (Portulaca oleracea L.)
- 2009
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Ingår i: Biotechnology letters. - : Springer Science and Business Media LLC. - 0141-5492 .- 1573-6776. ; 31:7, s. 1089-1101
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Tidskriftsartikel (refereegranskat)abstract
- Two full-length cDNA clones of PoleFAD2 and one full-length cDNA clone of PoleFAD6, encoding omega-6 fatty acid desaturases, the key enzymes for the conversion of oleic into linoleic acid, were isolated from purslane (Portulaca oleracea L.) leaves and seeds. The deduced amino acid sequence of both isoforms of PoleFAD2 showed higher similarities to other microsomal omega-6 desaturases then to PoleFAD6 or other plastidial orthologues, and vice versa. Expression analysis by RT-PCR showed that all genes are expressed in all tissues of purslane tested, but higher levels of mRNA accumulation were detected in reproductive organs and cells that proliferate rapidly or store lipids. Wounding affected the levels of mRNA accumulation of both, FAD2 and FAD6 genes in purslane leaves, while chilling stress affected only FAD2 transcript level. The expression patterns observed reflect the discrete roles of these genes in membrane synthesis for cell division, thylakoid development, and lipid storage or in the biosynthetic pathway for the production of signaling molecules that influence plant development or defense.
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| 3. |
- Brodelius, Maria, et al.
(författare)
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Fusion of farnesyldiphosphate synthase and epi-aristolochene synthase, a sesquiterpene cyclase involved in capsidiol biosynthesis in Nicotiana tabacum.
- 2002
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Ingår i: European Journal of Biochemistry. - : Wiley. - 0014-2956. ; 269:14, s. 3570-3577
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Tidskriftsartikel (refereegranskat)abstract
- A clone encoding farnesyl diphosphate synthase (FPPS) was obtained by PCR from a cDNA library made from young leaves of Artemisia annua. A cDNA clone encoding the tobacco epi-aristolochene synthase (eAS) was kindly supplied by J. Chappell (University of Kentucky, Lexington, KY, USA). Two fusions were constructed, i.e. FPPS/eAS and eAS/FPPS. The stop codon of the N-terminal enzyme was removed and replaced by a short peptide (Gly-Ser-Gly) to introduce a linker between the two ORFs. These two fusions and the two single cDNA clones were separately introduced into a bacterial expression vector (pET32). Escherichia coli was transformed with the expression vectors and enzymatically active soluble proteins were obtained after induction with isopropyl thio-beta-d-thiogalactoside. The recombinant enzymes were purified using immobilized metal affinity chromatography on Co2+ columns. The fusion enzymes produced epi-aristolochene from isopentenyl diphosphate through a coupled reaction. The Km values of FPPS and eAS for isopentenyl diphosphate and farnesyl diphosphate, respectively, were essentially the same for the single and fused enzymes. The bifunctional enzymes showed a more efficient conversion of isopentenyl diphosphate to epi-aristolochene than the corresponding amount of single enzymes.
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| 4. |
- Komaraiah, Palle, et al.
(författare)
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Growth behavior in plant cell cultures based on emissions detected by a multisensor array
- 2004
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Ingår i: Biotechnology progress (Print). - : Wiley. - 8756-7938 .- 1520-6033. ; 20:4, s. 1245-1250
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Tidskriftsartikel (refereegranskat)abstract
- The use of a multisensor array based on chemical gas sensors to monitor plant cell cultures is described. The multisensor array, also referred to as an electronic nose, consisted of 19 different metal oxide semiconductor sensors and one carbon dioxide sensor. The device was used to continuously monitor the off-gas from two plant cell suspension cultures, Morinda citrifolia and Nicotiana tabacum, cultivated under batch conditions. By analyzing the multiarray responses using two pattern recognition methods, principal component analysis and artificial neural networks, it was possible to monitor the course of the cultivations and, in turn, to predict (1) the biomass concentration in both systems and (2) the formation of the secondary metabolite, antraquinone, by M. citrifolia. The results identify the multisensor array method as a potentially useful analytical tool for monitoring plant process variables that are otherwise difficult to analyze on-line.
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| 5. |
- Lundberg, Peter, et al.
(författare)
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A phosphorus-31 nuclear magnetic resonance study of elicitor-mediated metabolic changes in Catharanthus roseus suspension cultures
- 1997
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Ingår i: In vitro cellular & developmental biology. Plant. - : Springer. - 1054-5476 .- 1475-2689. ; 33:4, s. 301-305
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Tidskriftsartikel (refereegranskat)abstract
- The induction of metabolic changes in suspension cultured cells of Catharanthus roseus upon elicitation has been investigated. Addition of a yeast glucan preparation to the growth medium resulted in induction of phenylalanine ammonia lyase. Phosphate uptake and metabolism of elicited cells was followed by 31P nuclear magnetic resonance. The uptake rate of Pi from the medium by oxygenated cells of C. roseus was reduced immediately after elicitation. Despite this reduced Pi uptake elicited cells had significantly increased amounts of ATP (twofold increase within 6 h). Cytoplasmic levels of Pi, phosphomonoesters, and Uridine Diphasphate glucose (UDP-Glc) were unaffected by eliciation. Furthermore, the cytoplasmic and vacuolar pH remained constant after addition of elicitor.
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| 6. |
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| 7. |
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| 8. |
- Gliszczynska, Anna, et al.
(författare)
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Sesquiterpene coumarins
- 2012
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Ingår i: Phytochemistry Reviews. - : Springer Science and Business Media LLC. - 1568-7767 .- 1572-980X. ; 11:1, s. 77-96
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Tidskriftsartikel (refereegranskat)abstract
- Plants have a long history as therapeutic tools in the treatment of human diseases and have been used as a source of medicines for ages. In search of new biologically active natural products, many plants and herbs used in traditional medicine are screened for natural products with pharmacological activity. In this paper, we present a group of natural products, the sesquiterpene coumarins isolated from plants, and describe their wide range of biological activity. Sesquiterpene coumarins are found in some plants of the families Apiaceae (Umbelliferae), Asteraceae (Compositae) and Rutaceae. The coumarin moiety is often umbelliferone (7-hydroxycoumarin) but scopo- letin (7-hydroxy-6-methoxycoumarin) and isofraxidin (7-hydroxy-6,8-dimethoxycoumarin) are also found. These coumarins are linked to a C15 terpene moiety through an ether linkage. Another group of sesquiter- pene coumarins is the prenylated 4-hydroxycoumarins where the link between the coumarin and the C15 terpene moiety is a C–C-bond at carbon 3 of the coumarin moiety. Finally, the prenylfurocoumarin-type sesquiterpenoids are a separate group of sesquiterpene coumarins based on the suggested biosynthetic pathway. Our relatively limited knowledge on the biosynthesis of sesquiterpene coumarins is reviewed.
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| 9. |
- Guo, Ming, et al.
(författare)
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A facile synthesis of molecularly imprinted polymers and their properties as electrochemical sensors for ethyl carbamate analysis
- 2018
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Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 8:69, s. 39721-39730
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Tidskriftsartikel (refereegranskat)abstract
- New molecularly imprinted polymers (MIPs), which exhibit specific recognition of ethyl carbamate (EC) have been synthesized and studied. In this process, EC was the template molecule and -cyclodextrin derivatives were employed as functional monomers in the molecular imprinting technique (MIT). An EC molecularly imprinted sensor (EC-MIS) was prepared by using MIT surface modification. The EC-MIS was characterized by cyclic voltammetry, electrochemical impedance spectroscopy and differential pulse voltammetry. EC detection performance, binding parameters and dynamics mechanism were investigated. The result showed that the synthetic route designed was appropriate and that new MIP and EC-MIS were successfully prepared. The EC-MIS exhibited a good molecular recognition of EC. A linear relationship between current and EC concentration was observed using cyclic voltammetry and the detection limit was 5.86 g L-1. The binding constant (K = 4.75 x 10(6) L mol(-1)) between EC and the EC-MIS, as well as, the number of binding sites (n = 1.48) has been determined. The EC-MIS recognition mechanism for the EC is a two-step process. The sensor was applied for the determination of EC in Chinese yellow wines, and the results were in good agreement with the gas chromatography-mass spectrometry (GC-MS) method.
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| 10. |
- Guo, Ming, et al.
(författare)
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alpha-Mangostin Extraction from the Native Mangosteen (Garcinia mangostana L.) and the Binding Mechanisms of alpha-Mangostin to HSA or TRF
- 2016
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:9
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Tidskriftsartikel (refereegranskat)abstract
- In order to obtain the biological active compound, alpha-mangostin, from the traditional native mangosteen (Garcinia mangostana L.), an extraction method for industrial application was explored. A high yield of a-mangostin (5.2%) was obtained by extraction from dried mangosteen pericarps with subsequent purification on macroporous resin HPD-400. The chemical structure of alpha-mangostin was verified mass spectrometry (MS), nuclear magnetic resonance (H-1 NMR and C-13 NMR), infrared spectroscopy (IR) and UV-Vis spectroscopy. The purity of the obtained alpha-mangostin was 95.6% as determined by HPLC analysis. The binding of native alpha-mangostin to human serum albumin (HSA) or transferrin (TRF) was explored by combining spectral experiments with molecular modeling. The results showed that amangostin binds to HSA or TRF as static complexes but the binding affinities were different in different systems. The binding constants and thermodynamic parameters were measured by fluorescence spectroscopy and absorbance spectra. The association constant of HSA or TRF binding to alpha-mangostin is 6.4832x10(5) L/mol and 1.4652x10(5) L/mol at 298 K and 7.8619x10(5) L/mol and 1.1582x10(5) L/mol at 310 K, respectively. The binding distance, the energy transfer efficiency between alpha-mangostin and HSA or TRF were also obtained by virtue of the Forster theory of non-radiation energy transfer. The effect of alpha-mangostin on the HSA or TRF conformation was analyzed by synchronous spectrometry and fluorescence polarization studies. Molecular docking results reveal that the main interaction between amangostin and HSA is hydrophobic interactions, while the main interaction between alpha-mangostin and TRF is hydrogen bonding and Van der Waals forces. These results are consistent with spectral results.
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