Alcoholysis
Mostrando 13-24 de 25 artigos, teses e dissertações.
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13. 70º aniversário do biodiesel em 2007: evolução histórica e situação atual no brasil
Periodically, during petroleum shortages, vegetable oils and their derivatives have been proposed as alternatives to petroleum diesel fuel. Different approaches have been proposed, including the use of pure vegetable oils (or blends) or their derivatives. Indeed, the use of fatty-acid methyl or ethyl esters (usually known as "biodiesel") produced by alcoholy
Química Nova. Publicado em: 2007
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14. Obtenção de ésteres etílicos e metílicos, por reações de transesterificação, a partir do óleo da palmeira Latino Americana macaúba - Acrocomia aculeata / Isolation of methilic and ethilic esters, by transferification reactions, from macauba trees oils- , Acrocomia aculeata
Ethyl esters and methyl esters (biodiesel) from oils of the fruits of the palm tree macauba (Acrocomia aculeata) were obtained by transesterification reactions performing the alcoholysis (methanolysis and ethanolysis) under homogeneous basic catalysis (using KOH, NaOH, CH3CH2OK, CH3CH2ONa CH3OK and CH3ONa), under homogeneous acid catalysis (using HCl and H2S
Publicado em: 2007
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15. Otimização das condições de produção de ésteres etílicos a partir de óleo de peixe com elevado teor de ácidos graxos ômega-3
The production of ethyl esters by alcoholysis is an alternative for splitting triacylglycerols due to the possibility of using low temperatures, which results in oxidative protection of the polyunsaturated fatty acids. Ethyl esters produced under mild conditions of temperature could be used as substrate for obtaining structured lipids. The reaction parameter
Química Nova. Publicado em: 2006-10
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16. Optimisation of the lipase-catalysed preparation of a nucleoside prodrug model using an experimental design methodology
The preparation of 2', 3'-di-O-hexanoyluridine (2) by a Candida antarctica B lipase-catalysed alcoholysis of 2', 3', 5'-tri-O-hexanoyluridine (1) was optimised using an experimental design. At 25 ºC better experimental conditions allowed an increase in the yield of 2 from 80% to 96%. In addition to the yield improvement, the volume reaction could be diminis
Química Nova. Publicado em: 2004-06
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17. Influence of substrate partition coefficient on the performance of lipase catalyzed synthesis of citronellyl acetate by alcoholysis
The enzymatic synthesis of selected low molecular weight esters such as acetate esters by direct esterification using acetic acid as acyl donor usually display low yields. The acetic acid changes the polarity of the reaction medium, which in this turn modifies the partitioning of water between the solid phase (enzyme preparation) and the liquid phase (substr
Brazilian Journal of Chemical Engineering. Publicado em: 2000-12
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18. Nonspecific alcoholysis, a novel endonuclease activity of human immunodeficiency virus type 1 and other retroviral integrases.
Retroviral integrase (IN) exhibits a previously unrecognized endonuclease activity which we have termed nonspecific alcoholysis. This action occurred at every position in nonviral DNA sequences except those near 5' ends and is clearly distinguished from, and was not predicted by, the site-specific alcoholysis activity previously described for IN at the proce
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19. Mapping Viral DNA Specificity to the Central Region of Integrase by Using Functional Human Immunodeficiency Virus Type 1/Visna Virus Chimeric Proteins
We previously described the construction and analysis of the first set of functional chimeric lentivirus integrases, involving exchange of the N-terminal, central, and C-terminal regions of the human immunodeficiency virus type 1 (HIV-1) and visna virus integrase (IN) proteins. Based on those results, additional HIV-1/visna virus chimeric integrases were des
American Society for Microbiology.
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20. Site-specific hydrolysis and alcoholysis of human immunodeficiency virus DNA termini mediated by the viral integrase protein.
Before integration of the human immunodeficiency virus (HIV) DNA, two nucleotides are removed from the 3' ends of the viral DNA by the integrase (IN) protein. We studied the chemistry of this reaction, and found that IN mediates site-specific hydrolysis of a phosphodiester bond, resulting in release of a dinucleotide. A class of alcohols (including glycerol,
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21. Gas chromatographic assessment of alcoholyzed fatty acids from yeasts: a new chemotaxonomic method.
An alternative chemotaxonomic method to methanolysis was developed for gas chromatographic assessment of fatty acids in whole yeast cells. Clinical and reference strains of the medically important yeasts Candida albicans, Torulopsis glabrata, and Saccharomyces cerevisiae were cultured for 48 h at 26 degrees C. Cellular lysis and transesterification were then
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22. Identification of amino acids in HIV-2 integrase involved in site-specific hydrolysis and alcoholysis of viral DNA termini.
The human immunodeficiency virus integrase (HIV IN) protein cleaves two nucleotides off the 3' end of viral DNA and subsequently integrates the viral DNA into target DNA. IN exposes a specific phosphodiester bond near the viral DNA end to nucleophilic attack by water or other nucleophiles, such as glycerol or the 3' hydroxyl group of the viral DNA molecule i
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23. Use of Patient-Derived Human Immunodeficiency Virus Type 1 Integrases To Identify a Protein Residue That Affects Target Site Selection
To identify parts of retroviral integrase that interact with cellular DNA, we tested patient-derived human immunodeficiency virus type 1 (HIV-1) integrases for alterations in the choice of nonviral target DNA sites. This strategy took advantage of the genetic diversity of HIV-1, which provided 75 integrase variants that differed by a small number of amino ac
American Society for Microbiology.
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24. Mapping domains of retroviral integrase responsible for viral DNA specificity and target site selection by analysis of chimeras between human immunodeficiency virus type 1 and visna virus integrases.
Human immunodeficiency virus type 1 (HIV-1) and visna virus integrases were purified from a bacterial expression system and assayed on oligonucleotide substrates derived from each terminus of human immunodeficiency virus type 1 and visna virus linear DNA. Three differences between the proteins were identified, including levels of specific 3'-end processing,