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  • 11
    Electronic Resource
    Electronic Resource
    Novel hydroxycarotenoids with improved antioxidative properties produced by gene combination in Escherichia coli (2000)
    [s.l.] : Nature America Inc.
    Nature biotechnology 18 (2000), S. 843-846 
    Details
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] We have used combinatorial biosynthesis to synthesize novel lipophilic carotenoids that are powerful cellular antioxidants. By co-expressing three different carotenoid desaturases in combination with a carotenoid hydratase, a cyclase, and a hydroxylase on compatible plasmids in Escherichia coli, we ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/78443
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  • 12
    Electronic Resource
    Electronic Resource
    New functional assignment of the carotenogenic genes crtB and crtE with constructs of these genes from Erwinia species (1992)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 90 (1992), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The role of carotenoid genes crtB and crtE has been functionally assigned. These genes were cloned from Erwinia into Escherichia coli or Agrobacterium tumefaciens. Their functions were elucidated by assaying early isoprenoid enzymes involved in phytoene formation. In vitro reactions from extracts of E. coli carrying the crtE gene or a complete carotenogenic gene cluster in which crtB was deleted showed an elevated conversion of farnesyl pyrophosphate (FPP) into geranylgeranyl pyrophosphate (GGPP). These results strongly indicate that the crtE gene encodes GGPP synthase. Introduction of the crtB gene into A. tumefaciens led to the conversion of GGPP into phytoene. This activity was absent in similar transformants with the crtE gene. Thus, the crtB probably encodes phytoene synthase, which was further supported by demonstration that phytoene accumulated in E. coli harboring both the crtB genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1992.tb05162.x
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  • 13
    Electronic Resource
    Electronic Resource
    Expression and biochemical characterization of the 1-HO-carotenoid methylase CrtF from Rhodobacter capsulatus (2003)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 222 (2003), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In purple bacteria, acyclic 1-methoxy carotenoids like spheroidene or spirilloxanthin are essential components of the photosynthetic apparatus. One of the last steps of their biosynthesis involves O-methylation of the 1-hydroxy group. The 1-HO-carotenoid methylase CrtF from Rhodobacter capsulatus catalyzing this type of reaction was expressed in Escherichia coli in an active form. It was then purified by affinity chromatography and biochemically characterized. The enzymatic reaction depends on S-adenosylmethionine as the only cofactor. By complementation in E. coli, the substrate specificity of the enzyme was determined. It could be shown that the enzyme converts not only all possible 1-hydroxy carotenoids in the spheroidene/1′-HO-spheroidene biosynthetic pathway of R. capsulatus but also carotenoid intermediates leading to the formation of spirilloxanthin in a pathway which is absent in R. capsulatus but present in related species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0378-1097(03)00302-1
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  • 14
    Electronic Resource
    Electronic Resource
    Structural and functional analysis of the gene cluster encoding carotenoid biosynthesis in Mycobacterium aurum A+ (2000)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 187 (2000), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The fragment containing the carotenoid gene cluster from Mycobacterium aurum A+, a 3,3′-dihydroxy-isoneriatene and 3-monohydroxy-isoneriatene accumulator, has been sequenced and the exposed eight genes are organised in two operons. The function of three of these genes, a phytoene desaturase (crtI), a phytoene cyclase (crtY) and a β-carotene desaturase (crtU), was demonstrated by complementation of M. aurum carotenoid mutants. The eight genes of the carotenoid cluster are highly homologous to other carotenoid gene clusters and thus this cluster is a candidate for its introduction into mycobacteria as a non-antibiotic reporter gene(s) as well as a source of new regulated promoters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2000.tb09143.x
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  • 15
    Electronic Resource
    Electronic Resource
    Molecular evolution of carotenoid biosynthesis from bacteria to plants (2002)
    Oxford, UK : Munksgaard International Publishers
    Physiologia plantarum 116 (2002), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: β-Carotene and derivatives are important pigments in plant photosynthesis. They are found not only in green plants but also accumulate in archea, prokaryotes and fungi. For β-carotene biosynthesis, enzymes are necessary to catalyse the formation of phytoene, several desaturation steps and cyclization reactions. This review is focused on the molecular phylogeny of the enzymes, the genes involved and their diversity. It outlines how genes and enzymes from prokaryotes and archea were modified to give rise to the corresponding plant constituents. In the cases of phytoene synthase, a direct line of evolution can be drawn. For other carotenogenic enzymes, new genes and enzymes have been acquired at certain stages of evolution. In addition, phytoene desaturases and lycopene cyclases are examples of convergent evolution of different types of enzymes, which are structurally completely unrelated but functionally identical. Finally, several gene duplications led to homologous enzymes with different catalytic functions including those involved in the synthesis of α-carotene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2002.1160401.x
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  • 16
    Electronic Resource
    Electronic Resource
    Biosynthesis of cyclic carotenoids: Biochemistry and molecular genetics of the reaction sequence (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 83 (1991), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Cyclic carotenids are found in the photosynthetic apparatus of higher plants. The biosynthesis of these pigments has been under investigation for two decades. Especially with in vitro systems from chromoplasts and unicellular cynaobacteria. new information has been obtained on the enzymatic reactions in carotenogenesis. Very recently, progress in the identification and cloning of several genes from the carotenogenic pathway has been made with bacteria, cyanobacteria and fungi. The new developments in biochemistry and molecular biology of cyclic carotenoids are reviewed, and the consequences of the results obtained by molecular genetics on the general understanding of the biosynthetic pathway of carotenoids are discussed, especially the desaturation and isomerization reactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1991.tb01300.x
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  • 17
    Electronic Resource
    Electronic Resource
    Activities of Cu-containing proteins in Cu-depleted pea leaves (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 72 (1988), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effect of Cu deficiency on Cu-containing enzymes and on their activities was studied with two subsequent generations of Cu-deficient pea plants (Pisum sativum L., cv. Progress) grown in low Cu2+ media. Cu deficiency caused growth inhibition and a decrease in photosynthesis as well as in the activities of 3 Cu-containing enzymes: diamine oxidase (EC 1.4.3.6), ascorbate oxidase (EC 1.10.3.3) and superoxide dismutase (EC 1.15.1.1). Determinations of photosynthetic electron-transport rates as well as the concentrations of several redox components showed that the target of Cu deprivation in the photosynthetic apparatus is the synthesis of Cu-containing plastocyanin which is positively correlated to the Cu content of the leaves. Inhibited formation of plastocyanin resulted in low activities of photosynthetic electron transport in photosystem I. Under Cu-deficient conditions, the activities of diamine oxidase and ascorbate oxidase were inhibited by about 50% in the first and 80% in the second generation of pea plants. Enzyme assays showed an inhibition of the activities of both the plastidic and cytoplasmic Cu/Zn-containing superoxide dismutases. An observed simultaneous increase of Mn-superoxide dismutase may be a compensation mechanism to partially maintain the total superoxide-dismutase activity under Cu-deficient conditions. This result indicates that the formation of superoxide-dismutase isoenzymes is interdependent and coordinated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1988.tb06382.x
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  • 18
    Electronic Resource
    Electronic Resource
    Inhibition of photosynthetic electron transport by amphotericin B (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 51 (1981), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: By assaying partial reactions of the photosynthetic electron transport system using thylakoids from spinach as well as from the algae Bumilleriopsis, Dunaliella, and Anabaena, it was demonstrated that the polyene antibiotic amphotericin B has no specific effect on plastocyanin. Pretreating spinach and algal thylakoids with this antibiotic decreased photosystem-II as well as photosystem-I activity regardless of whether the membranes contained plastocyanin or cytochrome c-553. Different sensitivity of cell-free electron transport activity against this antibiotic was observed due to the species used. With Dunaliella, the photosystem-II region was inhibited more strongly than photosystem-I, while Bumilleriopsis chloroplasts– although not containing plastocyanin – exhibited a stronger inhibition of the photosystem-I region. Apparently, amphotericin B mainly solubilizes redox compounds that form connecting pools in the photosynthetic electron transport chain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1981.tb04486.x
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  • 19
    Electronic Resource
    Electronic Resource
    Immunogold localization of phytoene desaturase in higher plant chloroplasts (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 88 (1993), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In situ location of phytoene desaturase, a key enzyme in the carotenoid biosynthesis pathway, has been investigated in chloroplasts from higher plants. For this purpose, an antiserum has been raised against the phytoene desaturase from the cyanobacterium Synechococcus PCC 7942 overexpressed in E. coli. The specifity of this antiserum was demonstrated by inhibition of the enzymatic desaturation reaction in vitro. The antiserum was further purified and immunoabsorbed with E. coli proteins. The resulting IgG-fraction was tested by western blotting against membrane proteins from chloroplasts of tobacco (Nicotiana tabacum L. cv. Samsun) and spinach (Spinacia oleracea L. cv. Atlanta). Apparent molecular masses of immunoreactive proteins were 62 and 64 kDa. A western blot of different membrane fractions of spinach chloroplasts (inner and outer envelopes, and thylakoids) indicated a localization of the phytoene desaturase in thylakoids. A post embedding immunogold microscopy procedure was employed. In these experiments the main labelling (79%) was associated with thylakoid membranes of tobacco chloroplasts. Of the counted colloidal gold particles, 16% were found in the stroma. Only 5% were detected in the envelope membranes. These results give clear evidence that at least the majority of phytoene desaturase molecules is localized within thylakoid membranes of higher plant chloroplasts and that the presence of the enzyme in the envelope is of minor significance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1993.tb05493.x
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  • 20
    Electronic Resource
    Electronic Resource
    Identification of carotenoids in Erwinia herbicola and in a transformed Escherichia coli strain (1990)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 71 (1990), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The yellow pigments of Erwinia herbicola Eho 10 and of a transformed Escherichia coli LE392 pPL376 have been identified as carotenoids. HPLC separation, spectra and in some cases mass spectroscopy demonstrated the presence of phytoene (15-cis isomer), β-carotene (all-trans, 9-cis and 15-cis), β-cryptoxanthin (3-hydroxy βcarotene), zeaxanthin (3,3′-dihydroxy β-carotene) and corresponding carotenoid glycosides. In addition, lycopene and β-carotene accumulated in the presence of the inhibitor 2-(4-chlorophenylthio)-triethylamine HCl. Carotenoid content in the transformed E. coli was two-fold higher than in E. herbicola. The pattern of the carotenoids was similar in the two organisms. Inactivation of the katF gene in E. coli resulted in an 85% loweing of carotenoid formation, as did the addition of 0.5% glucose to the medium. Suppression of carotenoid formation by inactivation of the katF gene lowered, but did not abolish, the protection offered by carotenoids against inactivation by α-terthienyl plus near-ultraviolet light (320–400 nm).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1990.tb03801.x
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