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Identification of some soluble esterases of the carrot (Daucus carota I.)Carino, Lourminia Almeda 14 December 1967 (has links)
Substrate and inhibitor specificities have been used to classify
esterases. The purpose of this work was to determine the substrate
and inhibitor specificities of the esterases in an aquous extract of
lyophilyzed carrots.
Esterase activity was determined manometrically at 37°C. The
optimum pH of the carrot esterases with several substrates varied
from 6.8 to 7.2, and a pH of 7.2 was used in this study. The carrot
extract hydrolyzed acetyl, propionyl and butyryl esters of phenol,
2-naphthol-6-SO₃Na and glycerol. As the acyl chain length was
increased, activity decreased. Long-chain naphthyl esters and
triolein were not hydrolyzed, which suggested the absence of lipase
in the extract. Lack of activity with choline esters indicated the
absence of cholinesterases. EDTA did not exhibit appreciable
activation of carrot esterases.
The effect of parathion, diisopropyl phosphorofluoridate (DFP) and tetraethyl pyrophosphate (TEPP) at various concentrations on the
rate of hydrolysis of the acetyl, propionyl and butyryl esters, of
phenol, 2-naphthol-6-SO₃Na and glycerol indicated the presence of
six esterases. Inhibitor and substrate specificities of five
esterases were similar to carboxylesterases (EC 3.1.1.1). The
sixth esterase was similar to arylester as e (EC 3.1.1.2). An enzyme
hydrolyzing DFP and TEPP was suggested in the carrot extract. / Graduation date: 1968
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Identification of some esterases of the green bean (Phaseolus vulgaris L.)Putnam, Teryl Beebe 08 March 1968 (has links)
This investigation was conducted to differentiate the esterases
in a water extract of freeze-dried green beans on the basis of inhibitor
and substrate specificities. An attempt was made to classify
these esterases according to the criteria used for animal esterases.
Activity of the esterases was measured manometrically using
the Gilson differential respirometer. Aqueous extracts of green
beans were found to hydrolyze the acetyl, propionyl, and n-butyryl
esters of glycerol, phenol, and 2-naphthol-6-SO₃Na. No hydrolysis
of triolein or long-chain 2-naphthol-6-SO₃Na esters was noted, indicating
the absence of lipases. A small amount of activity was observed
when the choline esters served as substrates, but this was
attributed to esterases other than cholinesterases. Optimum activity
of the extract on triacetin, tripropion, tributyrin, phenyl acetate,
and phenyl propionate occurred at pH 7.2.
The effects of organophosphorus inhibitors, diethyl p-nitrophenyl
thiophosphate, tetraethyl pyrophosphate, and diisopropylphosphorofluoridate,
at concentrations ranging from 10⁻¹ M to
10⁻¹⁰ M on the esterase activity was studied. These data show that
the green bean extract contains at least three esterases. One was
resistant to certain organophosphorus compounds, suggesting similarity
to animal arylesterases (aryl ester hydrolase, EC 3.1.1.2).
Various concentrations of organophosphorus compounds inhibited the
activity of the two other esterases. These were classified as carboxylesterases
(carboxylic ester hydrolase, EC 3.1.1.1). / Graduation date: 1968
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Characterization of NonR, an esterase that confers nonactin resistanceCox, James E., January 2004 (has links)
Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xiii, 195 p.; also includes graphics Includes bibliographical references (p. 177-195). Available online via OhioLINK's ETD Center
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Adaptabilidade diferencial das variantes moleculares "slow" e "fast" da esterase-5 de Drosophila mulleri /Thomazine, Vítor Baraldi January 2008 (has links)
Resumo: Vários trabalhos na literatura têm discutido a importância dos polimorfismos enzimáticos em relação ao estado de ser adaptado dos organismos. Nesse trabalho foram estudadas algumas propriedades bioquímicas das aloenzimas EST-5S e EST-5F de Drosophila mulleri, que poderiam estar relacionadas às diferenças em valores adaptativos em indivíduos que apresentam essas variantes enzimáticas. Os resultados sugerem que a aloenzima EST-5S apresenta maior resistência à desnaturação térmica e a agentes caotrópicos, bem como maior atividade em altas concentrações salinas. Os resultados do experimento de produtividade a 29º C mostram que os indivíduos homozigotos para o alelo Est-5S deixam mais descendentes que os indivíduos homozigotos para o alelo Est-5F. Quanto as caractetísticas cinéticas, essas aloenzimas não diferem de forma significante. Os valores de Vmax e Km obtidos para as enzimas não purificadas foram, respectivamente, para a EST-5S: 32,54 µM/min e 1,43 mM, e para a EST-5F: 33,34 µM/min e 1,54 mM. A purificação das aloenzimas foi obtida pela separação em SDS-PAGE seguida da remoção dos géis, eluição em agitador magnético para a difusão das enzimas e posterior concentração desse material em membrana filtrante de 50 kDa (Millipore). O concentrado foi então analisado quanto à atividade esterásica e quanto à pureza (SDS-PAGE). Ambas as aleloenzimas apresentaram uma massa molecular entre 66 e 68 kDa para a subunidade, em SDS-PAGE. Os resultados do presente estudo não são concordantes com a hipótese de neutralidade para a manutenção dos polimorfismos, tanto em populações naturais como de laboratório, indicando a atuação da seleção natural sobre as aleloenzimas estudadas. / Abstract: Several works in literature have discussed the importance of the enzymatic polymorphisms in respect to the state of being adapted of the organisms. In this work, some biochemical properties of Drosophila mulleri of the allozymes EST-5S and EST-5F, which could be related to the differences in fitness values in individuals that present those enzymatic variants, were studied. The results suggest that the EST-5S allozyme presents larger resistance on the thermic denaturation and the chaotropics agents, as well as higher activity in elevated salt concentrations. The results of the productivity experiment at 29°C show that the homozygous individuals to the Est-5S allele let more offspring than the homozygous individuals to the Est -5F allele. Regarding the kinetic characteristics, those allozymes do not differ in a significant way. The Km and Vmax values obtained for crude extracts allozymes were, respectively, to the EST-5S: 32,54 µM/min and 1,43 mM, and to the EST-5F: 33,34 µM/min and 1,54 mM. The purification of the allozymes was obtained by the separation on SDS-PAGE followed by their removal from gels, elution in magnetic shaker for the diffusion of the enzymes and concentration of this material in filtrant membranes of 50 kDa (Millipore). The concentrated materials were then analyzed regarding to their enzymatic activity and to the purity (SDS PAGE). Both allozymes presented subunit molecular weights around 66 and 68 kDa on SDS PAGE. The results of the present study do not agree to neutrality hypothesis for polymorphisms maintenance, in natural and laboratory populations, indicating a natural selection action of the on the studied allozymes. / Orientador: Carlos Roberto Ceron / Coorientador: Gustavo Orlando Bonilla Rodriguez / Banca: Hamilton Cabral / Banca: Fátima Pereira de Souza / Mestre
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Nonspecific esterases in human tissues evidence for their involvement in steroid metabolism and in carcinogenesis /Lund-Pero, Margaretha. January 1995 (has links)
Thesis (doctoral)--Lund University, 1995. / Added t.p. with thesis statement inserted.
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Nonspecific esterases in human tissues evidence for their involvement in steroid metabolism and in carcinogenesis /Lund-Pero, Margaretha. January 1995 (has links)
Thesis (doctoral)--Lund University, 1995. / Added t.p. with thesis statement inserted.
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Multiple forms of carboxylesterases in the green bean (Phaseolus vulgaris L.) and pea (Pisum sativum L.)Veerabhadrappa, Patnagere Siddaveera Sheety 09 December 1968 (has links)
Esterase activity of an aqueous extract of the green bean was
separated into fourteen bands, while aqueous extracted pea esterases
revealed seven bands, by polyacrylamide-gel electrophoresis. The
fourteen bands of bean esterase activity formed three groups; slow,
intermediate and fast moving. α-Naphthyl acetate, propionate, and
n-butyrate and AS naphthol acetate were hydrolyzed at various rates
by the bean and pea esterases. No hydrolysis of β-naphthyl laurate
was observed, indicating the absence of a lipase in the aqueous
extracts of these vegetables. Since all the esterase bands active
toward α-naphthyl acetate were inhibited by organophosphorus compounds
(diisopropylphosphorofluoridate, diethyl p-nitrophenyl thiophosphate
and diethyl p-nitrophenyl phosphate), these esterases were
classified as carboxylesterases (carboxylic ester hydrolase, EC
3.1.1.1).
To study the carboxylesterases of the green bean in greater
detail, a protamine sulfate treated aqueous extract was separated
into three fractions (S₁, S₂ and S₃) by chromatography on Sephadex
G-100. Subsequent analysis of each fraction by polyacrylamide-gel
electrophoresis demonstrated the presence of the slow moving group
in fraction S₁, slow and intermediate moving groups in fraction S₂
and the fast moving group in fraction S₃. Hence, these studies suggest
that the three groups of esterase activity in beans were dissimilar
in molecular size and the relative molecular size was
slow > intermediate > fast moving group.
Chromatography of fraction S₁ on carboxymethyl (CM) cellulose
with sodium chloride linear-gradient elution resulted in three fractions
(CM₁, CM₂ and CM₃). Similarly, fraction S₂ yielded three
fractions (DE₁, DE₂ and DE₃), while fraction S₃ produced two
fractions (DE₄ and DE₅), by chromatography on microgranular
diethylaminoethyl (DEAE) cellulose. Polyacrylamide-gel electrophoresis
revealed the presence of the first three bands of the slow
moving group in CM₁ and only the first two bands in CM₂. DE₁
possessed mainly the first two bands and DE₂ the last two bands of
the five bands in the slow moving group. The five bands of the intermediate
moving group of esterase activity was found only in fraction
DE₃. The first two bands of the four bands of the fast moving group
were separated into fraction DE₄, while the last two bands were in
DE₅.
Nine substrates and various concentrations of three inhibitors
were used to characterize some of the fractions obtained from ion-exchange
chromatography. Although most of the fractions hydrolyzed
the substrates used in this study, each fraction differed to some
extent in substrate specificity. Inhibitor studies indicated the
presence of a sensitive and a resistant component of esterase activity
in each fraction studied. These results suggest that the esterase
fractions were composed of two enzymes. To account for the fourteen
bands of esterase activity a hypothetical model of polymers
consisting of two monomers was proposed. This hypothesized model
suggests that the slow moving group contained six pentamers, the
intermediate group five tetramers and the fast moving group four
trimers. Most characteristics of the carboxylesterases of beans
observed in these studies could be explained on the basis of the
hypothetical model. / Graduation date: 1969
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The development of biomarkers in freshwater insects for the biological monitoring of pollutionParker, Penelope Judy-Ann Nicole January 1996 (has links)
No description available.
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The role of intestinal esterases in the absorption and metabolism of phthalate diestersWhite, Russell Donald January 1979 (has links)
No description available.
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Characterization and modification of fluorogenic substrate coated particles for use as enzyme probesOlsen, Greta A. 08 1900 (has links)
No description available.
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