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Katrina Cornish - One of the best experts on this subject based on the ideXlab platform.
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initiator independent and initiator dependent rubber biosynthesis in Ficus Elastica
Archives of Biochemistry and Biophysics, 2006Co-Authors: Stephanie C Espy, Jay D Keasling, Javier Castillon, Katrina CornishAbstract:The rubber-producing tree, Ficus Elastica (the Indian rubber tree), requires the same substrates for rubber production as other rubber-producing plants, such as Hevea brasiliensis (the Brazilian or Para rubber tree), the major source of commercial natural rubber in the world, and Parthenium argentatum (guayule), a widely studied alternative for natural rubber production currently under commercial development. Rubber biosynthesis can be studied, in vitro, using purified, enzymatically active rubber particles, an initiator such as FPP, IPP as the source of monomer, and a metal cofactor such as Mg2+. However, unlike H. brasiliensis and P. argentatum, we show that enzymatically active rubber particles purified from F. Elastica are able to synthesize rubber, in vitro, in the absence of added initiator. In this paper, we characterize, for the first time, the kinetic differences between initiator-dependent rubber biosynthesis, and initiator-independent rubber biosynthesis, and the effect of cofactor concentration on both of these processes.
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Some Rheological Properties of Latex from Parthenium argentatum Gray Compared with Latex from Hevea brasiliensis and Ficus Elastica
Journal of Polymers and the Environment, 2002Co-Authors: Katrina Cornish, Jenny L. BrichtaAbstract:Latex was purified from Parthenium argentatum Gray (guayule), Hevea brasiliensis Müll. Arg. (the Brazilian or para rubber tree), and Ficus Elastica Roxb. (the Indian rubber tree) in ammonium alginate at pH 10. The rheological properties of the different latices (rubber particle suspensions) were determined and compared using flow temperature ramps. Latex from all three species became more viscous with increasing rubber particle concentration and decreasing temperature. At any particular temperature and concentration, latex from F. Elastica was by far the most viscous, whereas the H. brasiliensis latex was the least viscous. In addition, the tendency for the latex to coagulate increased with increasing temperature and increasing particle concentration. F. Elastica latex was highly sensitive to temperature, H. brasiliensis latex was the least sensitive, and P. argentatum latex demonstrated intermediate properties. The underlying causes of these differences in latex rheology are not clear but may partially relate to the particle size (largest in F. Elastica and smallest in H. brasiliensis ), the particle size distribution, and/or to the considerable differences in the biochemical components of the monolayer biomembrane that surrounds the various rubber particles. Differences in the molecular weight of the rubber contained within the rubber particles seem less likely to play a role because the particles remain intact in this study.
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composition of rubber particles of hevea brasiliensis parthenium argentatum Ficus Elastica and euphorbia lactiflua indicates unconventional surface structure
Plant Physiology and Biochemistry, 1997Co-Authors: Deborah J Siler, Katrina Cornish, Goodrich M Tanrikulu, A E Stafford, T A MckeonAbstract:Natural rubber (cis-1,4-polyisoprene) is formed inside plant cells from allylic diphosphate initiators and isopentenyl diphosphate, and packaged in subcellular rubber particles. In addition to rubber. rubber particles contain proteins. which vary in size in different species. Rubber transferase [EC 2.5.1.20], the enzyme that catalyzes the cis-1,4 polymerization of isoprene into rubber, is particle bound. Since membrane lipids have been identified in extracts of Heivea brasiliensis rubber particles, it has been suggested that rubber particles are covered by a half-unit membrane. We have examined the fatty acid and lipid composition of rubber particles from four rubber producing species. H. brasiliensis, Parthenium argentatum, Ficus Elastica, and Euphorbia lactiflua. We demonstrate that although rubber particles from all four species contain significant amounts of phospholipids, glycolipids and sterols. there appears to be insufficient membrane lipid to constitute a half-unit membrane. Our results suggest that the rubber particle surface is a mosaic of protein, conventional membrane lipids and other components. The lipid covering may be a remnant of the rubber particle's origin in a unit membrane, with the addition of non-conventional components. including a large amount of non-phospholipid phosphate containing material. possibly polyisoprene mono- or diphosphate.
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characterization of cis prenyl transferase activity localised in a buoyant fraction of rubber particles from Ficus Elastica latex
Plant Physiology and Biochemistry, 1996Co-Authors: Katrina Cornish, Deborah J SilerAbstract:We investigated rubber biosynthesis in Ficus Elastica, a latex-producing plant species. Rubber particles were purified and enzyme activity was assayed by following the incorporation of radiolabel, from 14 C-isopentenyl diphosphate, into newly synthesised rubber (cis-1,4-polyisoprene). We characterised the rubber particle-bound F. Elastica cisprenyl transferase (rubber transferase), and describe the association of the active enzyme with a buoyant fraction of latex rubber particles. Also, we provide experimental data that may explain how isolated F. Elastica rubber particles were mistakenly believed to be enzymatically inert.
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immunoinhibition of rubber particle bound cis prenyl transferases in Ficus Elastica and parthenium argentatum
Phytochemistry, 1994Co-Authors: Katrina Cornish, Deborah J Siler, Okkoo K GrosjeanAbstract:Abstract A cis -prenyl transferase (‘rubber transferase’) catalyses the polymerization of isoprene units, derived from isopentenyl diphosphate, into natural rubber ( cis -1,4-polyisoprene). Cis -prenyl transferase activity is firmly associated with cytoplasmic rubber particles but the membrane-bound enzyme has yet to be identified. We have compared two different species, Ficus Elastica and Parthenium argentatum , which produce predominantly short chain and long chain rubber, respectively. The two species have disparate rubber particle protein complements. Antigenic similarities between the rubber particle proteins may include their cis -prenyl transferases, which likely contain some structural features in common. Cis -prenyl transferase activity in F. Elastica rubber particles was specifically inhibited by affinity-purified polyclonal IgG raised against a protein (LPR) purified from F. Elastica rubber particles. Thus, LPR appears to contain the cis -prenyl transferase active site. Anti-LPR IgG also specifically inhibited cis -prenyl transferase activity in rubber particles from P. argentatum . Thus, an anti-LPR IgG recognized similar epitopes at or near the active site of both the F. Elastica and P. argentatum cis -prenyl transferases. This is the first time that an antibody to a rubber particle protein has been shown to specifically inhibit cis -prenyl transferase activity, and could lead to the isolation of the enzyme from P. argentatum .
Rehab H Abdalla - One of the best experts on this subject based on the ideXlab platform.
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phytochemical and biological study of Ficus Elastica roxb var decora growing in egypt
Zagazig Journal of Pharmaceutical Sciences, 2002Co-Authors: Maher Eidomiaty, Mahmoud Abdelaal, Maged Abouhashem, Rehab H AbdallaAbstract:Phytochemical investigation of light petroleum and ethyl acetate extracts of leaves and stem of Ficus elastic Roxb, var, decora (Family Moraceae) resulted in the isolation of a new natural compound viz.1-0-caffaeovl-D- mannitol, Other separated compounds were moretenone, glutinol, moretenol, lupeol, B-sitosterol, sakuranin and kaempferol-3-0-rutinoside. The structures of these compounds were elucidated using spectroscopic and chemical evidences and by comparison with those reported in the literature. Biological screening was also carried out to reveal that the total alcoholic extract and the terpenoid fraction of the unsapnifiable matter (USM) showed significant anti-inflammatory and analgesic activities, while the total alcoholic extract showed a mild anti –diabetic activity. The anti-inflammatory activity of the terpenoidal fraction of USM was found to outweigh that of a marketed product.
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macro and micromorphological study of the root stem leaves and sheath of Ficus Elastica roxb var decora family moraceae
Zagazig Journal of Pharmaceutical Sciences, 2002Co-Authors: Maher Eldomiaty, Mahmoud Abdelaal, Maged Abouhashem, Rehab H AbdallaAbstract:The macro- and micromorphological study of Ficus Elastica Roxb var. decora, was carried out with the aim of finding out the characteristic features of the different organs of the plant in both entire and powdered forms.
Deborah J Siler - One of the best experts on this subject based on the ideXlab platform.
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composition of rubber particles of hevea brasiliensis parthenium argentatum Ficus Elastica and euphorbia lactiflua indicates unconventional surface structure
Plant Physiology and Biochemistry, 1997Co-Authors: Deborah J Siler, Katrina Cornish, Goodrich M Tanrikulu, A E Stafford, T A MckeonAbstract:Natural rubber (cis-1,4-polyisoprene) is formed inside plant cells from allylic diphosphate initiators and isopentenyl diphosphate, and packaged in subcellular rubber particles. In addition to rubber. rubber particles contain proteins. which vary in size in different species. Rubber transferase [EC 2.5.1.20], the enzyme that catalyzes the cis-1,4 polymerization of isoprene into rubber, is particle bound. Since membrane lipids have been identified in extracts of Heivea brasiliensis rubber particles, it has been suggested that rubber particles are covered by a half-unit membrane. We have examined the fatty acid and lipid composition of rubber particles from four rubber producing species. H. brasiliensis, Parthenium argentatum, Ficus Elastica, and Euphorbia lactiflua. We demonstrate that although rubber particles from all four species contain significant amounts of phospholipids, glycolipids and sterols. there appears to be insufficient membrane lipid to constitute a half-unit membrane. Our results suggest that the rubber particle surface is a mosaic of protein, conventional membrane lipids and other components. The lipid covering may be a remnant of the rubber particle's origin in a unit membrane, with the addition of non-conventional components. including a large amount of non-phospholipid phosphate containing material. possibly polyisoprene mono- or diphosphate.
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characterization of cis prenyl transferase activity localised in a buoyant fraction of rubber particles from Ficus Elastica latex
Plant Physiology and Biochemistry, 1996Co-Authors: Katrina Cornish, Deborah J SilerAbstract:We investigated rubber biosynthesis in Ficus Elastica, a latex-producing plant species. Rubber particles were purified and enzyme activity was assayed by following the incorporation of radiolabel, from 14 C-isopentenyl diphosphate, into newly synthesised rubber (cis-1,4-polyisoprene). We characterised the rubber particle-bound F. Elastica cisprenyl transferase (rubber transferase), and describe the association of the active enzyme with a buoyant fraction of latex rubber particles. Also, we provide experimental data that may explain how isolated F. Elastica rubber particles were mistakenly believed to be enzymatically inert.
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immunoinhibition of rubber particle bound cis prenyl transferases in Ficus Elastica and parthenium argentatum
Phytochemistry, 1994Co-Authors: Katrina Cornish, Deborah J Siler, Okkoo K GrosjeanAbstract:Abstract A cis -prenyl transferase (‘rubber transferase’) catalyses the polymerization of isoprene units, derived from isopentenyl diphosphate, into natural rubber ( cis -1,4-polyisoprene). Cis -prenyl transferase activity is firmly associated with cytoplasmic rubber particles but the membrane-bound enzyme has yet to be identified. We have compared two different species, Ficus Elastica and Parthenium argentatum , which produce predominantly short chain and long chain rubber, respectively. The two species have disparate rubber particle protein complements. Antigenic similarities between the rubber particle proteins may include their cis -prenyl transferases, which likely contain some structural features in common. Cis -prenyl transferase activity in F. Elastica rubber particles was specifically inhibited by affinity-purified polyclonal IgG raised against a protein (LPR) purified from F. Elastica rubber particles. Thus, LPR appears to contain the cis -prenyl transferase active site. Anti-LPR IgG also specifically inhibited cis -prenyl transferase activity in rubber particles from P. argentatum . Thus, an anti-LPR IgG recognized similar epitopes at or near the active site of both the F. Elastica and P. argentatum cis -prenyl transferases. This is the first time that an antibody to a rubber particle protein has been shown to specifically inhibit cis -prenyl transferase activity, and could lead to the isolation of the enzyme from P. argentatum .
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a protein from Ficus Elastica rubber particles is related to proteins from hevea brasiliensis and parthenium argentatum
Phytochemistry, 1993Co-Authors: Deborah J Siler, Katrina CornishAbstract:Abstract Rubber particles, having high rubber transferase (RuT) activity, were isolated from Ficus Elastica latex. The predominant protein in these rubber particles is a large hydrophobic glycoprotein (termed LPR for large protein from rubber particles), with an apparent monomeric M r of 376 000 on SDS-PAGE. A M r of 750 000 was determined with native PAGE, indicating that LPR probably exists as a dimer. Antibodies raised to purified LPR recognized blotted intact F. Elastica rubber particles, as well as LPR, demonstrating that LPR is situated at or near the surface of the particles. Anti-LPR antibodies also recognized enzymatically active rubber particles and rubber particle proteins from two other rubber-producing plants, Hevea brasiliensis and Parthenium argentatum . This indicates that the rubber particles of all three rubber-producing species contain proteins with common antigenic determinants. Large proteins, similar in size to LPR, were found in preparations of rubber particles from H. brasiliensis and P. argentatum . These results are the first demonstration that rubber particles from different species contain similar proteins that may share common functions in rubber biosynthesis and/or rubber particle structure.
Maged Abouhashem - One of the best experts on this subject based on the ideXlab platform.
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phytochemical and biological study of Ficus Elastica roxb var decora growing in egypt
Zagazig Journal of Pharmaceutical Sciences, 2002Co-Authors: Maher Eidomiaty, Mahmoud Abdelaal, Maged Abouhashem, Rehab H AbdallaAbstract:Phytochemical investigation of light petroleum and ethyl acetate extracts of leaves and stem of Ficus elastic Roxb, var, decora (Family Moraceae) resulted in the isolation of a new natural compound viz.1-0-caffaeovl-D- mannitol, Other separated compounds were moretenone, glutinol, moretenol, lupeol, B-sitosterol, sakuranin and kaempferol-3-0-rutinoside. The structures of these compounds were elucidated using spectroscopic and chemical evidences and by comparison with those reported in the literature. Biological screening was also carried out to reveal that the total alcoholic extract and the terpenoid fraction of the unsapnifiable matter (USM) showed significant anti-inflammatory and analgesic activities, while the total alcoholic extract showed a mild anti –diabetic activity. The anti-inflammatory activity of the terpenoidal fraction of USM was found to outweigh that of a marketed product.
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macro and micromorphological study of the root stem leaves and sheath of Ficus Elastica roxb var decora family moraceae
Zagazig Journal of Pharmaceutical Sciences, 2002Co-Authors: Maher Eldomiaty, Mahmoud Abdelaal, Maged Abouhashem, Rehab H AbdallaAbstract:The macro- and micromorphological study of Ficus Elastica Roxb var. decora, was carried out with the aim of finding out the characteristic features of the different organs of the plant in both entire and powdered forms.
Mahmoud Abdelaal - One of the best experts on this subject based on the ideXlab platform.
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phytochemical and biological study of Ficus Elastica roxb var decora growing in egypt
Zagazig Journal of Pharmaceutical Sciences, 2002Co-Authors: Maher Eidomiaty, Mahmoud Abdelaal, Maged Abouhashem, Rehab H AbdallaAbstract:Phytochemical investigation of light petroleum and ethyl acetate extracts of leaves and stem of Ficus elastic Roxb, var, decora (Family Moraceae) resulted in the isolation of a new natural compound viz.1-0-caffaeovl-D- mannitol, Other separated compounds were moretenone, glutinol, moretenol, lupeol, B-sitosterol, sakuranin and kaempferol-3-0-rutinoside. The structures of these compounds were elucidated using spectroscopic and chemical evidences and by comparison with those reported in the literature. Biological screening was also carried out to reveal that the total alcoholic extract and the terpenoid fraction of the unsapnifiable matter (USM) showed significant anti-inflammatory and analgesic activities, while the total alcoholic extract showed a mild anti –diabetic activity. The anti-inflammatory activity of the terpenoidal fraction of USM was found to outweigh that of a marketed product.
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macro and micromorphological study of the root stem leaves and sheath of Ficus Elastica roxb var decora family moraceae
Zagazig Journal of Pharmaceutical Sciences, 2002Co-Authors: Maher Eldomiaty, Mahmoud Abdelaal, Maged Abouhashem, Rehab H AbdallaAbstract:The macro- and micromorphological study of Ficus Elastica Roxb var. decora, was carried out with the aim of finding out the characteristic features of the different organs of the plant in both entire and powdered forms.