Enantioselective Analysis
Mostrando 13-24 de 25 artigos, teses e dissertações.
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13. Enantioselective analysis of omeprazole in pharmaceutical formulations by chiral high-performance liquid chromatography and capillary electrophoresis
Foram desenvolvidos dois métodos sensíveis e simples baseados em cromatografia líquida de alta eficiência e eletroforese capilar (EC) para a análise enantiosseletiva de omeprazol em formulações. O omeprazol racêmico e (S)-omeprazol foram extraídos de comprimidos disponíveis comercialmente usando metanol:NaOH 2,5 mol L-1 (90:10, v/v). A separação
Journal of the Brazilian Chemical Society. Publicado em: 2004-04
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14. A Interação substrato-modificador e sua importância para a hidrogenação enantiosseletiva de alfa-cetoésteres
The heterogeneous asymmetric catalysis plays an important and crucial role in many chemical processes and has therefore become a growing and interesting field. The enantioselective hydrogenation of α-ketoesters is one of the best known examples of such process. Methyl pyruvate, which can be converted to (R)- and (S)-methyl lactate with an enantioselecti
Publicado em: 2004
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15. Microbial Transformation of Ibuprofen by a Nocardia Species
The carboxylic acid functional group of ibuprofen [α-methyl-4-(2-methylpropyl) benzene acetic acid] is reduced to the corresponding alcohol and subsequently esterified to the acetate derivative by cultures of Nocardia species strain NRRL 5646. The alcohol and ester microbial transformation products were isolated, and their structures were determined by 1H a
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16. Analysis of shorthorn sculpin antifreeze protein stereospecific binding to (2-1 0) faces of ice.
In this paper we report the results of our studies on the stereospecific binding of shorthorn sculpin antifreeze protein (AFP) to (2 -1 0) secondary prism faces of ice. Using ice crystal growth and etching techniques together with molecular modeling, molecular dynamics, and energy minimization, we explain the nature of preferential binding of shorthorn sculp
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17. Streptomyces Serine Protease (DHP-A) as a New Biocatalyst Capable of Forming Chiral Intermediates of 1,4-Dihydropyridine Calcium Antagonists
Streptomyces viridosporus A-914 was screened as a producer of an enzyme to effectively form chiral intermediates of 1,4-dihydropyridine calcium antagonists. The supernatant liquid of the growing culture of this strain exhibited high activity for enantioselective hydrolysis of prochiral 1,4-dihydropyridine diesters to the corresponding (4R) half esters. The r
American Society for Microbiology.
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18. Involvement of two alpha-ketoglutarate-dependent dioxygenases in enantioselective degradation of (R)- and (S)-mecoprop by Sphingomonas herbicidovorans MH.
Cell extracts of Sphingomonas herbicidovorans MH grown on (R)-mecoprop contained an enzyme activity that selectively converted (R)-mecoprop to 4-chloro-2-methylphenol, whereas extracts of cells grown on (S)-mecoprop contained an enzyme activity selective for the S enantiomer. Both reactions were dependent on alpha-ketoglutarate and ferrous ions. Besides 4-ch
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19. Exploring Nitrilase Sequence Space for Enantioselective Catalysis†
Nitrilases are important in the biosphere as participants in synthesis and degradation pathways for naturally occurring, as well as xenobiotically derived, nitriles. Because of their inherent enantioselectivity, nitrilases are also attractive as mild, selective catalysts for setting chiral centers in fine chemical synthesis. Unfortunately, <20 nitrilases hav
American Society for Microbiology.
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20. Mimics of the binding sites of opioid receptors obtained by molecular imprinting of enkephalin and morphine.
Molecular imprinting of morphine and the endogenous neuropeptide [Leu5]enkephalin (Leu-enkephalin) in methacrylic acid-ethylene glycol dimethacrylate copolymers is described. Such molecular imprints possess the capacity to mimic the binding activity of opioid receptors. The recognition properties of the resultant imprints were analyzed by radioactive ligand
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21. Roles of the Enantioselective Glutathione S-Transferases in Cleavage of β-Aryl Ether
Cleavage of the β-aryl ether linkage is the most important process in lignin degradation. Here we characterize the three tandemly located glutathione S-transferase (GST) genes, ligF, ligE, and ligG, from low-molecular-weight lignin-degrading Sphingomonas paucimobilis SYK-6, and we describe the actual roles of these genes in the β-aryl ether cleavage. Based
American Society for Microbiology.
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22. Identification of diamino acids in the Murchison meteorite
Amino acids identified in the Murchison chondritic meteorite by molecular and isotopic analysis are thought to have been delivered to the early Earth by asteroids, comets, and interplanetary dust particles where they may have triggered the appearance of life by assisting in the synthesis of proteins via prebiotic polycondensation reactions [Oró, J. (1961) N
National Academy of Sciences.
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23. High-Level Formation of Active Pseudomonas cepacia Lipase after Heterologous Expression of the Encoding Gene and Its Modified Chaperone in Escherichia coli and Rapid In Vitro Refolding
The lipase from Pseudomonas cepacia ATCC 21808 (recently reclassified as Burkholderia cepacia) is widely used by organic chemists for enantioselective synthesis and is manufactured from recombinant P. cepacia harboring on a plasmid the clustered genes for lipase and its chaperone. High levels of expression of inactive lipase (40%) in Escherichia coli were ac
American Society for Microbiology.
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24. Display of Bacterial Lipase on the Escherichia coli Cell Surface by Using FadL as an Anchoring Motif and Use of the Enzyme in Enantioselective Biocatalysis
We have developed a novel cell surface display system by employing FadL as an anchoring motif, which is an outer membrane protein involved in long-chain fatty acid transport in Escherichia coli. A thermostable Bacillus sp. strain TG43 lipase (44.5 kDa) could be successfully displayed on the cell surface of E. coli in an active form by C-terminal deletion-fus
American Society for Microbiology.