Showing papers on "Esterase published in 1989"
TL;DR: A greater than 40-fold difference in rates of chlorpyrifosoxon hydrolysis observed between rat (low activity) and rabbit sera (high activity) correlated well with the reported large differences in LD50 values for chlorp Pyrifos in these two animals, consistent with an important role of serum paraoxonase in detoxification of organophosphorus pesticides in vivo.
222 citations
TL;DR: The data suggest that the human kidney contains a membrane-bound carbonic anhydrase protein that differs from the cytoplasmic isozymes CA I, II, and III and the secretory form (CA VI) in the saliva.
125 citations
TL;DR: It is suggested that a spatial gradient of nutrient breakdown and absorption already exists in the morphologically and physiologically incompletely developed digestive system of larval coregonids.
Abstract: Using histochemical methods, morphofunctional aspects of the alimentary tract of larval coregonids were investigated. Larvae of Coregonus lavaretus were reared for 34 days with either zooplankton or one of two dry diets. Ontogeny, localization and diet-related modifications of the following enzymes were examined: trypsin (luminal digestion), aminopeptidase, maltase, alkaline phosphatase (brush border-bound digestion) and unspecific esterase (intracellular nutrient processing). All of the enzymes studied were present in 13-day-old larvae. Except for the intracellularly located unspecific esterase, there was an ontogenetic enhancement of enzyme staining intensities accompanied by a significant increase in the volume of the intestinal mucosa. Enzyme activities differed within and between intestinal regions. This finding suggests that a spatial gradient of nutrient breakdown and absorption already exists in the morphologically and physiologically incompletely developed digestive system of larval coregonids. Digestive enzyme activities were modified in response to the dietary regimen. There was no obvious correlation between enzymic response and growth performance of the larvae.
100 citations
TL;DR: Results, in addition to the finding of an N-linked carbohydrate, suggest that the two 60-kDa proteins are oriented on the luminal side of the endoplasmic membrane.
88 citations
TL;DR: With the removal of water, hydrolysis is reduced more than four orders of magnitude while transesterification is diminished only 10‐fold, and stability of the Candida lipase in water‐restricted environments is much greater than in water/organic single phase systems.
Abstract: We investigated the ability of several hydrolases to catalyze reactions with an abiotic water-insoluble substrate, carbonic acid diphenyl ester, also known as diphenyl carbonate (DPC). In single-phase water/organic systems, turnover numbers (TN) of greater than 2 x 10(4) min(-1)have been achieved for the hydrolysis of DPC. The K(m) values for the hydrolytic reaction were measured to be 200 microM and 330 microM for Candida cylindracea lipase and Porcine liver esterase, respectively. In addition to hydrolysis, we observed transesterification of carbonates with a wide variety of alcohol and phenol species. Transesterifications of DPC with bifunctional alcohols resulted in the synthesis of polycarbonates. We investigated the stability and transesterification activity of these enzymes in several water-restricted environments to limit competing hydrolysis reactions. We find that, with the removal of water, hydrolysis is reduced more than four orders of magnitude while transesterification is diminished only 10-fold (turnover numbers of 600 min(-1) in water-miscible systems to 60 min(-1) in water-restricted environments with pure Candida lipase). Stability of the Candida lipase in these water-restricted environments (half-life of longer than 3 days) is much greater than in water/organic single phase systems (5 h in 20% methanol). In addition, the Candida lipase displayed enantiomeric selectivity in transesterifications of DPC with racemic 2-butanol (greater than 80% ee).
88 citations
TL;DR: It is suggested that variation in haemolymph juvenile hormone esterase activity during the last stadium may play an important role in wingmorph determination in Gryllus rubens.
88 citations
TL;DR: Using a partial cDNA of this gene, genomic fragments generated by EcoR1 restriction enzyme in various laboratory and natural populations of Culex that are OP resistant are probed.
Abstract: Increased detoxification by esterases is a common mechanism of resistance to organophosphate (OP) insecticides in insects. Utilizing a partial cDNA of this gene, we probed genomic fragments generated by EcoR1 restriction enzyme in various laboratory and natural populations of Culex that are OP resistant
87 citations
TL;DR: The urinary leukocyte esterase test is a noninvasive and cost-effective screening method to detect urethritis among asymptomatic adolescent males and identified 38 culture-verified infections that otherwise would have remained undetected.
Abstract: We evaluated the ability of the urinary leukocyte esterase test to predict culture-verified chlamydial and gonococcal urethritis among asymptomatic adolescent males. Nine hundred forty-eight sexually active males provided first-catch urine samples for esterase screening, and 76 (8%) tested positive (≥1 + ). Among 435 boys who agreed to undergo urethral culture, the esterase was positive in 66 (15%),Chlamydia trachomatiswas isolated from 39 (9%), and Neisseria gonorrhoeae was isolated from 14 (3%). The sensitivity, specificity, and positive and negative predictive values for the esterase test were 72%, 93%, and 58% and 96%, respectively. Using the esterase test to screen asymptomatic males for urethritis, we identified 38 culture-verified infections that otherwise would have remained undetected. The urinary leukocyte esterase test is a noninvasive and cost-effective screening method to detect urethritis among asymptomatic adolescent males. (JAMA. 1989;262:2562-2566)
77 citations
TL;DR: Results showed that the cholesterol esterases in the liver and the pancreas are very similar and possibly identical proteins.
74 citations
TL;DR: The active site serine of the acetylesterase of influenza C virus was localized to amino acid 71 of the hemagglutinin-esterase protein by affinity labeling with 3H-labeled diisopropylfluorophosphate, suggesting that this viral enzyme is a serine hydrolase constituting a new family of serine esterases.
Abstract: The active site serine of the acetylesterase of influenza C virus was localized to amino acid 71 of the hemagglutinin-esterase protein by affinity labeling with 3H-labeled diisopropylfluorophosphate. This serine and the adjacent amino acids (Phe-Gly-Asp-Ser) are part of a consensus sequence motif found in serine hydrolases. Since comparative analysis failed to reveal esterase sequence similarities with other serine hydrolases, we suggest that this viral enzyme is a serine hydrolase constituting a new family of serine esterases. Furthermore, we found that the influenza C virus esterase was inhibited by isocoumarin derivatives, with 3,4-dichloroisocoumarin being the most potent inhibitor. Addition of this compound prevented elution of influenza C virus from erythrocytes and inhibited virus infectivity, possibly through inhibition of virus entry into cells.
66 citations
TL;DR: Cutinase from V. inaequalis belongs to the class high content of glycine, ahigh content of nonpolar amino acids, two of serine hydrolases, a characterisitic shared with other fungal cutinases, and a high degree of hydrophobicity.
Abstract: K61ler, W., and Parker, D. M. 1989. Purification and characterization of cutinase from Venturia inaequalis. Phytopathology 79:278-283. Venturia inaequalis was grown in a culture medium containing purified cutinase from V. inaequalis is optimal at a pH of 6 and thus different from apple cutin as the sole carbon source. After 8 wk of growth an esterase was the alkaline pH-optimum reported for other purified cutinases. The isolated from the culture fluid and purified to apparent homogeneity. The hydrolysis of the model esterp-nitrophenyl butyrate was less affected by the enzyme hydrolyzed tritiated cutin and thus was identified as cutinase. The pH. The esterase activity was strongly inhibited by diisopropyl purified cutinase is a glycoprotein with a molecular mass of 21-23 kg/ mol, fluorophosphate, and the phosphorylation of one serine was sufficient for as determined by various procedures. Remarkable structural features are a complete inhibition. Thus, cutinase from V. inaequalis belongs to the class high content of glycine, a high content of nonpolar amino acids, two of serine hydrolases, a characterisitic shared with other fungal cutinases. disulfide bridges, and a high degree of hydrophobicity. Cutin hydrolysis by
TL;DR: The oligotrophic biofilm was found to contain about twice as much extracellular esterase activity as the more eutrophic River Clywedog biofilm, although these activities also fluctuated during the colonization period.
Abstract: SUMMARY. 1. Extracellular hydrolytic enzyme activities and cell densities were monitored during undisrupted biofilm formation on pristine surfaces in two contrasting river sites in North Wales: an oligotrophic mountain stream (Nant Waen) and a mildly eutrophic river (River Clywedog).
2. Bacterial densities generally increased at both sites over a 33-day monitoring period. Densities in the eutrophic site were approximately 14 times greater than in the mountain stream.
3. Using fluorescent substrate analogues, biofilms from Nant Waen produced low, variable xylosidase and β-glucosidase activities. Biofilms from the more eutrophic River Clywedog produced higher xylosidase and β-glucosidase activities and detectable endopeptidase, though these activities also fluctuated during the colonization period.
4. Unlike the other activities measured, esterase activities in the River Clywedog were correlated with cell densities (P<0.05). When extracellular esterase activities per cell were calculated, the oligotrophic biofilm was found to contain about twice as much extracellular esterase activity as the more eutrophic River Clywedog biofilm.
TL;DR: This turbidimetric esterase assay has been used to determine the activities of cell-associated and excreted esterases produced by Lysobacter enzymogenes and Pseudomonas aeruginosa, and of lipolytic enzymes from porcine liver, Chromobacterium viscosum, Candida cylindracea, and wheat germ.
Abstract: A turbidimetric esterase assay was developed using a Tween 20 solution in the presence of CaCl2 and Lysobacter enzymogenes esterase (EC 3.1.1.1) as the enzyme source. The reaction was followed by m...
TL;DR: This is the first verified case of detoxication of an allelochemical by esterase enzymes in herbivores, and the biochemical adaptation has played an important role in the evolution of food plant preferences in P. glaucus subspecies.
Abstract: Phenolic glycosides, commonly occurring allelochemicals in the plant family Salicaceae, are differentially toxic to subspecies of the eastern tiger swallowtail and responsible for striking differences in the abilities of Papilio glaucus canadensis and P.g. glaucus to utilize the Salicaceae as food plants. This research was designed to test the hypothesis that particularly high esterase activity confers resistance to phenolic glycosides in P.g. canadensis. I conducted larval survival trials in which the phenolic glycosides salicortin and tremulacin were administered with and without inhibitors of the major detoxication enzymes. Results for P.g. canadensis showed that when esterases were inhibited, toxicity of the phenolic glycosides increased greatly. None of the inhibitors significantly increased toxicity of the compounds to P.g. glaucus. I also conducted in vitro assays of the major detoxication enzymes (polysubstrate monooxygenases, esterases, and glutathione transferases) in larval midguts. Soluble esterase activity was 3-fold higher in P.g. canadensis than in P.g. glaucus. Moreover, esterase activity was inducible by prior consumption of phenolic glycosides in P.g. canadensis but not in P.g. glaucus. Glutathione transferases may also be involved in the terminal metabolism of phenolic glycosides. This is the first verified case of detoxication of an allelochemical by esterase enzymes in herbivores. The biochemical adaptation has played an important role in the evolution of food plant preferences in P. glaucus subspecies.
TL;DR: Kinetic studies with various substrates show that the enzyme is specific for sialic acids and selectively cleaves acetyl groups in the 9-position, and shows little activity against a variety of other natural compounds bearing O-acetyl esters.
TL;DR: In this paper, a lipase was found to catalyze the regioselective hydrolysis at the secondary hydroxyl group of 2′-deoxy-3′,5′-di-O-hexanoyl pyrimidine nuclosides.
TL;DR: In this paper, the authors used a continuous spectrophotometric assay for the hydrolysis of p-nitrophenyl esters of fatty acids to determine the chain length specificity of the enzyme and its modulation by anions and apolipoproteins.
TL;DR: Horse liver esterase, used as its inexpensive commercial acetone powder, catalyzes the selective hydrolysis of methyl 2-alkyl-2-arylacetates to afford R(−)-2 -alkyl 2 -acetyl 2-arylacetic acids and S(+)-methyl 2 −alkyl -2-acetylacetates.
TL;DR: The established oxygen-insertion specificity of this enzyme coupled with an unequivocal absence of esterase activity allowed the nature of the oxygen insertion into 6-oxocineole by the enzyme from Rhodococcus C1 to be inferred and a reaction sequence for cleavage of both rings of 1,8-cineole to be proposed.
Abstract: SUMMARY: A Rhodococcus sp. (strain C1) was isolated by elective culture with 1,8-cineole as sole carbon source. 6-endo-Hydroxycineole and 6-oxocineole accumulated transiently during the latter part of the exponential growth phase and, together with 1,8-cineole, were oxidized rapidly by 1,8-cineole-grown cells. Although a putative 1,8-cineole monooxygenase was not detected in cell-free systems an induced 6-endo-hydroxycineole dehydrogenase and an induced NADPH-linked 6-oxocineole oxygenase were readily demonstrated. The lactone 5,5-dimethyl-4-(3′-oxobutyl)-4,5-dihydrofuran-2(3H)-one was isolated from oxygenation reactions with 6-oxocineole as substrate. This was not the immediate product of oxygenation but resulted from non-enzymic lactonization of the ring cleavage intermediate 3-(1-hydroxy-1-methylethyl)-6-oxoheptanoic acid during extraction procedures. 2,5-Diketocamphane 1,2-monooxygenase purified from (+)-camphor-grown Pseudomonas putida ATCC 17453 was also able to utilize 6-oxocineole as a substrate with formation of the same isolated product. The established oxygen-insertion specificity of this enzyme coupled with an unequivocal absence of esterase activity allowed the nature of the oxygen insertion into 6-oxocineole by the enzyme from Rhodococcus C1 to be inferred and a reaction sequence for cleavage of both rings of 1,8-cineole to be proposed. It provides an explanation for the reported isolation of (R)-5,5-dimethyl-4-(3′-oxobutyl)-4,5-dihydrofuran-2(3H)-one from culture media of Pseudomonas flava grown with 1,8-cineole.
TL;DR: The β,γ-epoxy esters (±)- 2 to 6 were synthetisized and the E -values of the kinetic resolution of 2, 3, 4, and 6 with PLE and the absolute configuration of the products of the hydrolysis were determined by the conversion to known compounds as discussed by the authors.
TL;DR: Strong evidence is provided that the 148 and 112 kD proteins are subunits of a multicomponent NTE complex and solubilization of active chicken brain NTE with the nondenaturing detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate is described.
TL;DR: A putative esterase gene (est) from Acinetobacter calcoaceticus RAG-1 has been cloned into Escherichia coli and esterase-positive clones exhibited high levels of ester enzyme activity even in intact cells.
TL;DR: The FP/Est test is a reliable method for detecting and monitoring of organophosphate resistance and can be used as a rough estimate of resistance levels to monitor resistance caused by increased esterase activity in mosquitoes and agricultural pests.
Abstract: A previously described filter paper test procedure for detecting of esterases involved in organophosphate insecticide resistance in the Culex pipiens L. complex was modified to permit quantification of esterase activity and resistance in single insects. The new procedure, FP/Est test, was used to survey organophosphate resistance in 11 field collections from seven states. Clear discrimination of increased activity was possible by visual inspection and by densitometric analysis. The proportion of insects with susceptible-like esterase activity was strongly correlated with (and often was not significantly different from) the proportion found to be susceptible by bioassay with chlorpyrifos, temephos, fenthion, and malathion, indicating that the FP/Est test is a reliable method for detecting and monitoring of organophosphate resistance. In addition, the 90th percentile of esterase activity in each collection was significantly correlated with the LC90 of each of the four insecticides, suggesting that the FP/Est test also can be used as a rough estimate of resistance levels. Application of the FP/Est test to monitor resistance caused by increased esterase activity in mosquitoes and agricultural pests is discussed.
Journal Article•
TL;DR: Esterases were more useful than malate dehydrogenases in identification of the major Meloidogyne species and the host plant had no effect on the nematode esterase or malate dehydration phenotypes.
Abstract: Nonspecific esterases and malate dehydrogenases of 1-5 females from 40 root-knot nematode populations from Portugal were analyzed by electrophoresis in 0.4-ram-thick polyacryl- amide gels. Fourteen major bands of esterase activity were detected, corresponding to 10 distinct phenotypes, Meloidogyne javanica and M. hapla had distinct species-specific phenotypes. Two phe- notypes occurred in M. arenaria. The most variability was found among M. incognita populations. Of the remaining two phenotypes, one was associated with M. hispanica and the other belonged to a new species. Three malate dehydrogenase phenotypes were discerned on the basis of particular combinations of the eight main bands of activity found. As previously found, esterases were more useful than malate dehydrogenases in identification of the major Meloidogyne species. The host plant had no effect on the nematode esterase or malate dehydrogenase phenotypes.
Patent•
26 Sep 1989
TL;DR: Sucrose derivatives partially acylated in each ring can be obtained by treating a fully or partially acylated sucrose derivative with an enzyme having sucrose esterase activity capable of removing at least one acyl group from each ring, generally comprising or being a component of a lipase, ester enzyme, amylase, α-galactosidase or protease preparation, the enzyme treatment being effected in an aqueous system.
Abstract: Sucrose derivatives partially acylated in each ring can be obtained by treating a fully or partially acylated sucrose derivative with an enzyme having sucrose esterase activity capable of removing at least one acyl group from each ring, generally comprising or being a component of a lipase, esterase, amylase, α-galactosidase or protease preparation, the enzyme treatment being effected in an aqueous system. Sucralose can be obtained by using this method to obtain a sucrose 2,3,6,3',4'-penta ester which can then be chlorinated and de-esterfied. Some of the penta acetates, tetraacetates and mixed acetates/butyrates are new compounds.
TL;DR: Cell extracts of Cenococcum graniforme have been found to contain hydrolytic enzymes that showed a high association with cell wall material, and the release of enzymes from the cells into the culture fluid appeared to occur only when the cells were undergoing autolysis.
Abstract: Cell extracts of Cenococcum graniforme have been found to contain the following hydrolytic enzymes: protease, esterase, alpha-d-galactopyranosidase, beta-d-galactopyranosidase, alpha-d-mannopyranosidase, beta-d-xylopyranosidase, alpha-d-glucopyranosidase, beta-d-glucopyranosidase, and alkaline phosphatase. Sulfatase, inorganic pyrophosphatase, and beta-d-mannopyranosidase were not detected in the extracts. beta-d-Xylopyranosidase and alpha-d-mannopyranosidase were most active in the neutral pH range, protease and phosphatase were most active in the alkaline pH range, and other enzymes were most active in the acidic pH range. These enzymes showed a high association with cell wall material, and the release of enzymes from the cells into the culture fluid appeared to occur only when the cells were undergoing autolysis. Alkaline phosphatase in C. graniforme is a constitutive enzyme, and examination of the alkaline phosphatase following a purification of 265-fold produced the following characteristics: pH optimum of 9.5, M(r) of 60,000, K(m) of 2.1 x 10 M for p-nitrophenylphosphate, and activation energy for hydrolysis of the substrate at 9.9 kcal (1 cal = 4.184 J)/mol.
TL;DR: Comparing the complete derived amino acid sequence for D2 to two cloned and sequenced eukaryotic esterases and examining the requirement of the D2 gene product for development suggests that D2 encodes an esterase function required for proper aggregation and subsequent development.
TL;DR: In this paper, a variety of chemically defined compounds were tested to characterize the substrate specificity of the influenza C virus esterase and to determine whether a substrate could be found that would be useful in an assay to detect the virus.
Abstract: A variety of chemically defined compounds were tested to characterize the substrate specificity of the influenza C virus esterase and to determine whether a substrate could be found that would be useful in an assay to detect the virus. Two new substrates, alpha-naphthyl acetate and alpha-naphthyl propionate, were identified; alpha-naphthyl acetate was employed to develop an assay specific for influenza type C virus in MDCK cells. The assay was sufficiently sensitive to detect esterase activity in a single cell and distinguished influenza C virus infections from those of types A and B viruses. Infected cells could be detected as early as 8 h postinfection, with maximal enzyme detection occurring at 24 h. Assay of influenza C virus in the chorioallantoic or amniotic fluid of infected eggs was performed by applying fluids directly onto nitrocellulose strips and then incubating with alpha-naphthyl acetate. Both the cellular and nitrocellulose-bound assays are rapid, inexpensive, and easy to perform, offering advantages for use in clinical laboratories. Images
TL;DR: The results show the existence of an alcohol-binding site and a competitive partitioning of the acyl-enzyme intermediate between water and alcohols and a number of four active centres is determined for the tetrameric carboxylesterase.
Abstract: The carboxylesterase (serine esterase, EC 3.1.1.1) from Sulfolobus acidocaldarius was purified 940-fold to homogeneity by an improved purification procedure with a yield of 57%. In the presence of alcohols the enzyme catalyses the transfer of the substrate acyl group to alcohols in parallel to hydrolysis. The results show the existence of an alcohol-binding site and a competitive partitioning of the acyl-enzyme intermediate between water and alcohols. Aniline acts also as a nucleophilic acceptor for the acyl group. On the basis of titration with diethyl p-nitrophenyl phosphate, a number of four active centres is determined for the tetrameric carboxylesterase. The sequence of 20 amino acid residues at the esterase N-terminus and the amino acid composition are reported.