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Showing papers on "Esterase published in 1984"



Journal ArticleDOI
TL;DR: Results reconfirm the importance of esterification in the absorption of exogenous cholesterol and demonstrate that cholesterol esterase plays an essential role in the regulation of the absorption process.

122 citations


Journal ArticleDOI
TL;DR: Various detoxifying enzymes, including microsomal oxidases, glutathione S -transferases, esterases, epoxide hydrolase, and DDT-dehydrochlorinase were assayed in adult worker bees using midguts as the enzyme source, suggesting that the high susceptibility of honey bees to insecticides is not due to low detoxication capacity.

120 citations


Journal ArticleDOI
TL;DR: The varying activities of the individual hydrolases were influenced in parallel by a variety of inhibitors, indicating that the purifiedhydrolases possessed a relatively broad specificity and were not mixtures of more specific enzymes.

97 citations


Journal ArticleDOI
TL;DR: Five purified carboxylesterases from rat liver microsomes show a differing capacity for the hydrolysis of ester- and amide-type drugs, and the purified nonspecific esterase with the lowest isoelectric point is not involved in the metabolism of the drugs mentioned.

91 citations


Journal ArticleDOI
TL;DR: The chemical and immunological properties of five closely related microsomal serine hydrolases (carboxylesterases) from rat liver have been compared to evaluate whether they are variants of a single protein or independent proteins.

53 citations


Journal ArticleDOI
TL;DR: The anti-allatotropin, precocene, was used to treat adult males to determine if juvenile hormone levels affect the activity of esterase 6 and may allow for further exploration of the hormonal regulation of reproductive processes in Drosophila.

48 citations


Journal ArticleDOI
TL;DR: The high sensitivity of reagent strip leukocyte esterase testing for pyuria makes it a valuable screening test that should lead to the elimination of many needless urine cultures and microscopic examinations.

45 citations


Journal ArticleDOI
TL;DR: Esterolytic activity of the various enzymic reagents is related to the source and matrix of the cholesterol esterase and must be considered with respect to proper selection of calibration materials for serum cholesterol measurement.
Abstract: Esterolytic activity of three enzymic cholesterol reagents was evaluated with use of human serum-based reference materials. Primary cholesterol standards were used to calibrate the enzymic methods, and incomplete cholesteryl ester hydrolysis was measured as the bias between the enzymic cholesterol values and corresponding reference values. The average biases observed with eight reference specimens were 0.15, -1.16, and -7.24%, respectively, for a commercial enzymic reagent with microbial cholesterol esterase, a commercial reagent with an animal source of esterase, and a Centers for Disease Control (CDC) reagent preparation with a microbial cholesterol esterase. By liquid chromatography, we examined the respective specificities of the three esterase reagent preparations and found that the preparations differ in the rate and specificity of catalysis of cholesteryl ester hydrolysis. The CDC reagent was only partly active towards cholesteryl arachidonate, which probably accounts for most of the negative bias of this reagent. Esterolytic activity of the various enzymic reagents is related to the source and matrix of the cholesterol esterase and must be considered with respect to proper selection of calibration materials for serum cholesterol measurement.

44 citations


Journal ArticleDOI
TL;DR: The pathway was supported in vivo by demonstrating that topical application of 3H-labeled tetradecanyl acetate onto the insect gland resulted in the formation of [3H]tetradecanol and [3 H]t Petradecanoic acid, thus providing evidence that all three enzymes were functional in the living insects.

41 citations


Journal ArticleDOI
TL;DR: Results strongly suggest that F. solani pisi generates extremely similar, if not identical, polyesterases to degrade cutin and suberin when these polymers constitute the sole carbon source.
Abstract: Fusarium solani pisi isolate T-8 was found to grow with suberin from potato tuber periderm as the sole source of carbon. The extracellular fluid from such cultures catalysed the hydrolysis of p-nitrophenyl butyrate and radioactive apple cutin. The major portion of this esterase was bound to the suberin-containing mycelial mat from which the activity could be washed out with a 0·4% Triton X-100 solution. All of this esterase activity was contained in two isozymes which were purified by a passage of the Triton wash through QAE-Sephadex followed by ion exchange chromatography with SP-Sephadex. Both isozymes were homogeneous as judged by polyacrylamide gel electrophoresis with or without SDS. Each showed a molecular weight of 23 000. Analysis of the aliphatic components released by the esterase from suberin by combined GLC/MS showed that all classes of monomers were released by the esterase. The two enzymes were very similar in their catalytic properties and amino acid composition to two isozymes of cutinase isolated from the extracellular fluid of the same fungus grown on apple cutin. The esterases had one disulphide bridge and no free SH group just as previously noted for fungal cutinases. Ouchterlony double diffusion analyses showed that the two esterases isolated from suberin-grown cells cross-reacted with complete fusion of the precipitin lines when tested with antibodies generated against the two cutinases generated by cutin-grown cells. These results strongly suggest that F. solani pisi generates extremely similar, if not identical, polyesterases to degrade cutin and suberin when these polymers constitute the sole carbon source.

Journal ArticleDOI
TL;DR: Results indicate that the methionyl residue modified by phenacylbromide is located in the S1′ binding site of the enzyme, which is significantly higher than with unmodified carboxypeptidase Y.
Abstract: Treatment of carboxypeptidase Y with14C-iodoacetamide caused a drastic reduction in the peptidase activity towards FA-Phe↓Leu-OH while the esterase activity towards FA-Phe↓OMe, the amidase activity towards FA-Phe↓Nh2 and the peptidyl amino acid amide hydrolase activity towards FA-Phe↓Gly−NH2 were much less affected. The loss of peptidase activity could be correlated with the incorporation of a single equivalent of reagent and it was demonstrated that the site of reaction was a methionyl residue, thus forming a sulfonium derivative. Analogous methionyl modifications were performed: carboxypeptidase Y modified with phenacylbromide hydrolysed substrates with bulky leaving groups in the P 1 ′ position,i.e.OEt,-OBzl,-Gly−NH2,-Gly−OH, and-Leu-OH, at reduced rates while substrates with small groups in that position, i.e.,-OMe and-NH2, were hydrolysed with increased rates. These results indicate that the methionyl residue modified by phenacylbromide is located in the S 1 ′ binding site of the enzyme. Similar results were obtained with carboxypeptidase Y modified with m-nitrophenacylbromide and p-nitrophenacylbromide. The increase in amidase activity and decrease in peptidyl amino acid amide hydrolase activity of carboxypeptidase Y following modification with phenacylbromide, m-nitrophenacylbromide, and p-nitrophenacylbromide was exploited in deamidation of peptide amides. These modified enzymes deamidated peptid amides with the exception of those containing a C-terminal glycyl or seryl residue in yields of 80–100% which is significantly higher than with unmodified carboxypeptidase Y.

Journal ArticleDOI
TL;DR: A soluble wheat esterase, catalyzing a cleavage of the mass-produced plasticizer chemical, bis(2-ethyl-hexyl)phthalate (DEHP), has been discovered as discussed by the authors.
Abstract: A soluble wheat esterase, catalyzing a cleavage of the mass-produced plasticizer chemical, bis(2-ethyl-hexyl)phthalate (DEHP), has been discovered. Although wheat plants and seeds as well as cultured wheat cells contained more than 12 non-specific esterase activities, only a single protein with a marked preference for a substrate chain-length of 6–8 carbon atoms was active with DEHP. This enzyme is shown to differ from all previously characterized plant lipases and esterases. The enzyme was purified 10-fold from wheat plants and 280-fold, to electrophoretic homogeneity, from cultured wheat cells. An apparent functional molecular mass of 38000 Da and an apparent subunit molecular mass of 22000 Da were determined. Inhibitor experiments pointed to the catalytic involvement of a serine residue. Cleavage of DEHP by the purified enzyme was about 104 times slower than cleavage of 4-nitrophenyl octanoate. This was consistent with previous evidence for a rate-limiting role of the esterase reaction in DEHP metabolism by intact wheat cells.

Journal ArticleDOI
TL;DR: The findings suggest that lipase and esterase activity in human milk which is donated to hospitals and stored frozen can make a valuable contribution to fat digestion in the newborn infant, but pasteurization destroys the enzyme.
Abstract: In a study of human milk obtained in the first month of lactation, lipase and esterase activity were assayed. Bile salt-stimulated lipase (BSSL) and bile salt-stimulated esterase (BSSE) activities in colostrum were similar to corresponding enzyme activities in transitional milk and in mature milk. BSSL and BSSE were significantly (P less than 0.001) correlated to one another, which suggests that lipase and esterase activities in milk are due to the same enzyme. When milk was allowed to stand at room temperature, in a refrigerator, or subjected to freezing and thawing, wide fluctuations were observed in lipase and esterase activities, but there was no systematic tendency for enzyme activity to increase or decrease. Heating milk to various temperatures between 40-55 degrees C resulted in progressive loss of enzyme activity. The activation energy for the process which inactivates the enzyme was found by linear regression to the Arrhenius plot to be 2 X 10(5) J X mole-1. Our findings suggest that lipase and esterase activity in human milk which is donated to hospitals and stored frozen can make a valuable contribution to fat digestion in the newborn infant, but pasteurization destroys the enzyme.

Journal ArticleDOI
TL;DR: An intracellular aminopeptidase (alpha-aminoacyl-peptide hydrolase (cytosol), EC 3.4.11.1) isolated from cell extracts of Lactobacillus acidophilus R-26 was purified 634-fold to homogeneity.

Journal ArticleDOI
TL;DR: In three different experiments that were designed to eliminate contaminating mucus and pancreatic enzymes from the lumen of the small intestine, it was observed that the activities of cholesterol esterase and amylase in intestinal cytosol and whole homogenate decreased in parallel fashion.

Journal ArticleDOI
TL;DR: The results suggest a dual role for esterases in resistance mechanisms; a catalyst for hydrolysis of malathion and fenvalerate, and a binding protein for the oxygen analogs of other OP insecticides, both of which would protect the intrinsic target, acetylcholinesterase, from inhibition.

Journal ArticleDOI
TL;DR: Hydrolysis of acyl-S-mercaptoethanol and ac-1-glycerol and the ATP-dependent reduction of the released fatty acids to aldehyde for the luminescent reaction were demonstrated, raising the possibility that the immediate source of fatty acids for this reaction in vivo could be the membrane lipids and/or the fatty acid synthetase system.

Journal ArticleDOI
TL;DR: The results suggested the existence of multiple forms of esterases with overlapping substrate specificity in the house fly, and the involvement of additional mechanisms, including phosphorotriester hydrolase activity, was suggested.

Journal Article
TL;DR: Enterobacter sakazakii is the new species name introduced in 1977 for yellow-pigmented strains originally designated as yellow Enterobacter cloacae, and all of the six E.sakazAKii strains isolated from powdered milk specimens were found to produce Tween 80 esterase after 7 days of incubation at 25 degrees C and 37 degrees C.
Abstract: Enterobacter sakazakii is the new species name introduced in 1977 for yellow-pigmented strains originally designated as yellow Enterobacter cloacae. All of the six E.sakazakii strains isolated from powdered milk specimens were found to produce Tween 80 esterase after 7 days of incubation at 25 degrees C and 37 degrees C. From E.cloacae it is distinguishable by reactions in four, or even three, biochemical tests, i.e. by production of yellow pigment, positive production of Tween 80 esterase and by non-fermentation of sorbite and mucate; from the Serratia species it can be differentiated by the negative test for lecithinase production.

Journal ArticleDOI
TL;DR: Analytical electrofocusing of the 2630-fold purified JHE reveals two distinct JHE activity bands, one of which does not contain any detectable 1-naphthylacetate activity and is comprised of three closely positioned protein bands of pH 4.75 ± 0.05.


Journal ArticleDOI
TL;DR: The correlation between esterase-6 band intensities and malathion LT50 in 3-day-old adults of the mosquito Aedes aegypti was significantly high and available evidence indicates that ester enzyme-6 is one resistance mechanism among others.
Abstract: The correlation between esterase-6 band intensities and malathion LT50 in 3-day-old adults of the mosquito Aedes aegypti was significantly high. Three strains of mosquito were used: a field-tolerant and highly laboratory-selected strain, Villa Palmeras (VP); a population of Villa Palmeras that had not been laboratory selected for resistance and had regressed, Unselected Villa Palmeras (UVP); and a susceptible strain never exposed to malathion, Triple Marker (TM). Following horizontal electrophoresis on polyacrylamide gels, the intensity of esterase bands was measured by scanning densitometry. Band intensities in VP were significantly greater than in TM, but those in VP and UVP were not significantly different. The reciprocal F1's of the crosses between VP and TM showed intermediate resistance and an intermediate esterase intensity significantly different from either parental strain. Available evidence indicates that esterase-6 is one resistance mechanism among others. The measurement of esterase-6 intensity as a guide to field tolerance of Ae. aegypti to malathion is considered briefly.

Journal ArticleDOI
TL;DR: The in vivo inhibition data of topically treated larvae at equimolar amounts of the tested compounds indicated rapid penetration, and the stability of the inhibition was higher for the phosphoramidothioate than for the trifluoromethylketones.

Journal ArticleDOI
TL;DR: Calf pregastric esterase (PGE) was purified from calf gullet tissues and allowed calculation of an "average hydrophobicity" (Bigelow index) of 1150 cal/residue, indicating that calf PGE is relatively hydrophobic, being similar to proteins such as alpha-lactalbumin and bovine serum albumin in average hydrophOBicity.

Journal ArticleDOI
TL;DR: Using in vitro methods, juvenile hormone (JH) esterase activity and alpha-Naphthylacetate esterases increased during the first gonotrophic cycle of the house cricket, Acheta domesticus: peaks of their activity could be observed concomitant with peaks of JH esters activity.

Journal ArticleDOI
TL;DR: Two JH carboxylesterases were isolated from haemolymph of vitellogenic females by anion exchange chromatography and purification resulted in an approx.

Journal ArticleDOI
TL;DR: Three components with arginine esterase activities were found in the venom of the Chinese pit viper (Agkistrodon halys Pallas) and they were identified as bradykinin releasing, thrombin-like and fibrinogenolytic enzymes respectively.

Journal ArticleDOI
TL;DR: A new medium was developed for detecting esterase and gelatinase activities in aerobic and facultatively anaerobic bacteria and the results showed agreement between the reactions in the new medium and those obtained by conventional techniques.
Abstract: A new medium was developed for detecting esterase and gelatinase activities in aerobic and facultatively anaerobic bacteria. The new medium was tested with various strains of bacteria and the results showed agreement between the reactions in the new medium and those obtained by conventional techniques. The new medium is more economical and may be used for a rapid differentiation of Serratia, Aeromonas and Vibrio species from biochemically similar bacteria.

Journal ArticleDOI
TL;DR: Predicting that a 6-month-old boy carries the tumor-predisposing retinoblastoma gene is predicted using determinations of esterase D isoenzymes in the members of a family with hereditary retinOBlastoma.