Showing papers on "Esterase published in 1986"
TL;DR: The finding that selection by pesticides may result in the amplification of genes encoding detoxifying enzymes in whole, normally developed, reproducing insects emphasizes the biological importance of this mechanism and opens new areas of investigation in pesticide resistance management.
Abstract: An esterase gene from the mosquito Culex quinquefasciatus that is responsible for resistance to a variety of organophosphorus (OP) insecticides was cloned in lambda gt11 phage. This gene was used to investigate the genetic mechanism of the high production of the esterase B1 it encodes in OP-resistant Culex quinquefasciatus Say (Tem-R strain) from California. Adults of the Tem-R strain were found to possess at least 250 times more copies of the gene than adults of a susceptible strain (S-Lab). The finding that selection by pesticides may result in the amplification of genes encoding detoxifying enzymes in whole, normally developed, reproducing insects emphasizes the biological importance of this mechanism and opens new areas of investigation in pesticide resistance management.
346 citations
TL;DR: It is demonstrated that fungal esterase and xylanase activities act cooperatively in hydrolyzing acetyl xylan, and that the two activities also act synergistically to liberate acetyl residues.
Abstract: Xylan exists in many plants in an acetylated form, a circumstance largely neglected in studies of its breakdown by microbial enzymes. The present investigation demonstrates that fungal esterase and xylanase activities act cooperatively in hydrolyzing acetyl xylan. In the absence of esterase, xylanases break only a limited number of glycosidic bonds. Both the extent and rate of breakdown increase when esterase is present. The two activities also act synergistically to liberate acetyl residues. The prominent effect of esterase action on the hydrolysis of glycosidic bonds suggests that its role will require consideration in processes where acetyl xylan is a substrate.
237 citations
TL;DR: The serine esterase activity is secreted by lymphocytes that have been stimulated with the calcium ionophore A23187 and could play an active role in cell-mediated killing.
169 citations
151 citations
TL;DR: Both BEPAT and methoprene, a juvenile hormone analogue, caused a reduction in egg hatch when applied topically 30 h after a blood meal, demonstrating that the decline in juvenile hormone levels after aBlood meal is necessary for normal egg development and suggesting thatThe decline is mediated, at least in part, by juvenile hormone esterase.
133 citations
TL;DR: Observations confirm the traditional view that C. elegans development is "mosaic," with each cell following a defined independent program of gene expression.
111 citations
TL;DR: Peptidoglycan isolated from Gram-positive bacteria initiated the activation of the enzymes in plasma at a concentration of a few ng/ml, strongly suggest that the active principle of bacterial cell walls is peptidogly can.
107 citations
TL;DR: These studies confirmed the quantitative changes in E4 protein previously reported and established that the increased esterase activity in P. humuli also arises from the production of more protein, or proteins, homologous to E4.
Abstract: An antiserum was prepared against carboxylesterase E4, the enzyme conferring resistance in Myzus persicae (Sulzer) to a wide range of insecticides, and the immunoglobulin G (IgG) fraction was purified from it by affinity chromotography. Interactions of the antiserum and IgG with aphid homogenates and the purified esterase proteins were studied by immune diffusion, immunoelectrophoresis and enzyme-linked immunosorbent assay (ELISA). In M. persicae, the interactions were specific for E4 and its closely-related mutant form, FE4, and except for Phorodon humuli (Schrank), there was no cross-reaction with homogenates of the nine other aphid species examined. These studies confirmed the quantitative changes in E4 protein previously reported and established that the increased esterase activity in P. humuli also arises from the production of more protein, or proteins, homologous to E4. Resistance of M. persicae could be characterized by immunoelectrophoresis even after preservation of the insects in 30% ethanol. Although ELISA could also be used to identify resistance, a simpler immunoplate assay was developed based on measuring the esterase activity of E4 retained when the enzyme bound to IgG. This assay discriminates well between the three resistant M. persicae variants common in the field in the UK, and its simplicity allows the study of large numbers of insects.
101 citations
TL;DR: A theory is proposed to explain the physical bases of the ionic control of the activity of an enzyme system, located on a plant cell surface, and probably involved in cell-wall synthesis and extension, which may display a very high co-operativity of its response to slight changes of pH.
Abstract: A theory is proposed to explain the physical bases of the ionic control of the activity of an enzyme system, located on a plant cell surface, and probably involved in cell-wall synthesis and extension. The model, which is based on various previously published experimental results, involves several assumptions: a cell-wall pectin methyl esterase de-esterifies pectins and thus creates the fixed negative charges of the cell wall; various enzymes incorporate uncharged carbohydrates in cell-wall material; cell-wall extension implies the sliding of cellulose microfibrils; the enzymes responsible for carbohydrate incorporation are activated by protons in the pH range 4-8 and have very similar pH dependencies: the cell-wall pectin methyl esterase is inhibited by protons in the same pH range. The mathematical derivation of this model, written in the form of a hypercycle, indicates that it is equivalent to a set of two antagonistic enzyme reactions: an enzyme reaction conditioned by pectin methyl esterase which results in the increase of fixed charge density of the cell wall; a number of 'growth enzymes', which produce extension and building up of the cell wall and therefore a decrease of charge density. The mathematical study of this model shows it may display a very high co-operativity of its response to slight changes of pH. This cooperativity means that the cell wall charge density may dramatically increase or decrease, within a very narrow pH range. The steep response of this system appears to be the direct consequence of different pH sensitivities of pectin methyl esterase and of the other cell-wall enzymes involved in cell growth. Calcium, which tightly binds to the cell wall, may diminish or even suppress this abrupt charge transition. This model suggests a novel theory of the ionic control of cell-wall expansion. The very basis of this theory is the existence of an electrostatic potential difference, delta psi, between the inside and the outside of the cell wall. When this delta psi value is large, the local proton concentration is high. Therefore the enzymes involved in cell wall extension and building up are active, but pectin methyl esterase is not. Therefore, the cell wall extends and the charge density decreases. The delta psi value then declines, as well as the local proton concentration. Under these conditions, the pectin methyl esterase becomes activated, whereas the 'growth enzymes' are not. This activation of pectin methyl esterase restores the initial, or an even higher, electrostatic potential difference, which in turn results in a decrease of local pH.(ABSTRACT TRUNCATED AT 400 WORDS)
81 citations
TL;DR: The availability of this clone should allow for the cloning of the RB gene by chromosome walking; the diagnosis of genetic defects such as retinoblastomas and Wilson disease, whose genes are closely linked to the esterase D gene; and the exploration of the large family of human ester enzyme genes.
Abstract: Retinoblastoma, the most common intraocular tumor, represents one of the prototypes of inheritable cancers. To elucidate the mechanisms that give rise to this tumor, the retinoblastoma gene (RB) must be molecularly cloned. The difficulty encountered in cloning the gene is that little of its function or structure is known. The human esterase D gene, on the other hand, has been localized cytogenetically to the same sub-band of chromosome 13q14:11 as the RB gene. The esterase D gene thus provides a convenient starting point for cloning the RB gene. In this communication, we describe the isolation of the esterase D cDNA clone. Its identification is based on three lines of evidence. This cDNA encodes a protein immunologically related to the esterase D protein. The deduced amino acid sequences of this clone contain sequences identical to the three CNBr-cleaved peptides of the esterase D protein. This clone is mapped to the chromosome 13q14 region by Southern genomic blotting using different deletion mutants. The availability of this clone should allow for the cloning of the RB gene by chromosome walking; the diagnosis of genetic defects such as retinoblastomas and Wilson disease, whose genes are closely linked to the esterase D gene; and the exploration of the large family of human esterase genes.
74 citations
TL;DR: Gabonase, an enzyme which acts on fibrinogen and factor XIII in uniquely thrombin-like ways, was purified to electrophoretic homogeneity from the venom of Bitis gabonica and exhibits strong N alpha-p-tosyl-L-arginine methyl esterase activity.
TL;DR: In this paper, the authors report the intraceIlular esterolytic activities of Lactobacillus helveticus, L. bulgaricus, and L. acidophilus using several nitrophenyl derivatives of fatty acids.
Abstract: Summary In the present work we report the intraceIlular esterolytic activities of Lactobacillus helveticus, L. bulgaricus, L. lactis and. L. acidophilus using several nitrophenyl derivatives of fatty acids. AIl the tested lactobacilli show activities towards derivatives up to five carbons. P-nitrophenyl derivatives were hydrolysed significantly faster than the O-nitrophenyl derivatives. L. lactis and L. acidophilus strains can be distinguished from the strains of L. bulgaricus and L. helveticus by their higher esterase activities. After electrophoretic separation in 7 % acrylamide gels, zymograms showed three main bands distributed from RF 0.5 to RF 0.3 for L. helveticus. From L. bulgaricus, four bands were distinguished, three of them with electrophoretic mobilities similar to main bands in L. helveticus. Sorne of the L. acidophilus and L. lactis strains were distinguished by the presence of up to three addition al bands of lower electrophoretic mobility. On the other hand, the specifie activity of esterase increased gradually during the growth of L. helveticus. The trend was different for the esterase system of L. bulgaricus since activity was almostsimilar during the different stages of growth. Generally, the optimum temperature for esterase production by the thermophilic lactobaciIli was found to be 40-45° C. Little specifie activity was detected after cell growth either at 35 or 55° C. In conclusion, thermophilic lactobacilli possess a complex esterolytic system. It is specifie towards short chain fatty acids. Unfortunately, difIerences between strains are two little for use of these results as a tool for the taxonomy of Lactobacilli. However, this type of enzymatic activities could be used as an indicator for the detection and the control of strains in mixed lactic acid bacteria cultures.
TL;DR: The experimental results offer experimental support to two important ideas discussed in the preceding paper, namely that pectin methyl esterase reaction builds up the Donnan potential at the cell surface, and that this response may be co-operative with respect to pH.
Abstract: The pectin methyl esterase from soybean cell walls has been isolated and purified to homogeneity. It is a protein with a relative molecular mass close to 33 000. The enzyme is maximally active at a pH close to 8 and its pH dependence may be explained by a classical Dixon model, where the two interconvertible enzyme ionization states coexist. The outflux of protons from cell walls, upon raising the ionic strength, may be taken as an indirect estimate of the fixed charge density. If the cell-wall fragments are pre-incubated at pH values between 5 and 9, the outflux of protons rises with the pH of pre-incubation. This implies, as postulated from the theory developed in the preceding paper, that alkaline pH favours the activity of pectin methyl esterase and that this enzyme effectively generates the fixed negative charges of the cell wall. Therefore the pectin methyl esterase reaction builds up the Donnan potential, delta psi, at the cell surface. The cell-wall charge density, estimated from the proton outflux, as well as from the titration of methyl groups on the cell wall, reaches a maximum between the third and the fourth day of growth. While the cell-wall volume increases and reaches a plateau, the fixed charge density increases at first and then declines. This is understandable if one assumes that the building up of a high charge density is a co-operative phenomenon and that the local pH inside the wall rises during cell growth. When both the cell-wall volume and the charge density increase together, this suggests that the local pH inside the wall lies within the critical pH range associated with the steep response of the system. When the cell-wall volume increases together with a decrease of the fixed charge density, the local pH should have dropped below this critical pH range. Under these conditions the pectin methyl esterase remains inactive, or poorly active. As the number of fixed negative charges increases, calcium becomes tightly bound to cell walls. This binding is so tight that the net charge density is minimum when the calcium concentration is maximum. The experimental results, presented above, offer experimental support to two important ideas discussed in the preceding paper, namely that pectin methyl esterase reaction builds up the Donnan potential at the cell surface, and that this response may be co-operative with respect to pH.
TL;DR: Human esterase D (carboxylesterase; carboxylic-ester hydrolase, EC 3.1.1), a genetic marker of retinoblastoma, was purified to biochemical homogeneity from erythrocytes and expressed 3-fold in a promonocytic cell line treated with phenobarbital but not with phorbol myristate acetate, suggesting that ester enzyme D may have a role in detoxification.
Abstract: Human esterase D (carboxylesterase; carboxylic-ester hydrolase, EC 3.1.1.1), a genetic marker of retinoblastoma, was purified to biochemical homogeneity from erythrocytes. The purification scheme including carboxymethylcellulose, phenyl-Sepharose, chromatofocusing, and hydroxylapatite chromatographies resulted in a 10,000-fold purification of the enzyme with 15% recovery of total activity. The Km of esterase D was estimated to be 10 X 10(-6) M using 4-methylumbelliferyl acetate as substrate. The enzymatic activity was inhibited by p-chloromercuribenzoate and HgCl2, suggesting an important role of SH group(s) in enzyme function. Specific rabbit polyclonal and mouse monoclonal antibodies against esterase D were prepared and recognized either denatured or native human esterase D protein. Moreover, the polyclonal antibodies immunoprecipitated a polypeptide with a molecular mass of about 33-34 kDa from various cell lines of different mammalian species, indicating that the esterase D protein is highly conserved. The highest levels of this enzyme were found in liver and kidney. Furthermore, the expression of esterase D was enhanced 3-fold in a promonocytic cell line treated with phenobarbital but not with phorbol myristate acetate, suggesting that esterase D may have a role in detoxification. The availability of the homogeneous protein and its specific antibodies allows for cloning of the esterase D gene and facilitates studies of retinoblastomas.
TL;DR: The rate and enantioselectivity of pig liver esterase catalysed hydrolysis of meso diacetates and diesters, the magnitude of the effect being strongly dependent on the nature of substrate as discussed by the authors.
TL;DR: Six species of Glomus have been characterized by subjecting spore extracts to polyacrylamide gel electrophoresis and selective enzyme staining and recommendations of suitable enzymes to distinguish between these fungi are given.
Abstract: Six species of Glomus have been characterized by subjecting spore extracts to polyacrylamide gel electrophoresis and selective enzyme staining. The banding patterns of six enzymes (esterase, glutamate oxaloacetate transaminase, hexokinase, malate dehydrogenase, peptidase and phosphoglucomutase) were diagnostic for each species and recommendations of suitable enzymes to distinguish between these fungi are given. Spores of Glomus caledonium which had been produced in a variety of soils and hosts gave the same banding patterns with four enzymes.
TL;DR: Among the 610 strains investigated, 316 electrophoretic types (distinctive combinations of allozymes of the four varieties of esterases) were distinguished, illustrating high esterase polymorphism.
Abstract: Summary: To determine whether enzyme electrophoretic polymorphism in Escherichia coli populations was influenced by environmental background, the mobilities of four electrophoretically variable esterases (A, B, C and I) were examined. The distinction between isolates was established by significant differences in the electrophoretic distribution and the genetic diversity coefficient of individual esterases. Principal components analysis on each population and on all strains revealed three groups of allozymes. The first, characterized by slow electrophoretic mobilities of esterase B, was frequently observed in strains obtained from human extra-intestinal infections and rarely in commensal organisms. The second, characterized by fast mobilities of esterases A and B, was frequently found in animal isolates. The third, characterized by prominence of the most common mobilities of esterases B and A, was recovered in all populations. These results were confirmed by discriminant analysis. Among the 610 strains investigated, 316 electrophoretic types (distinctive combinations of allozymes of the four varieties of esterases) were distinguished, illustrating high esterase polymorphism.
TL;DR: Amino acid analysis indicated that both enzyme forms have similar amino acid compositions, and the kinetic constants for hydrolysis of p-nitrophenyl phosphate as catalysed by sunflower seed acid phosphatase were independent of pH in the range 3-5.
TL;DR: Body scales of the silk mothAntheraea polyphemus contain an esterase which can degrade the female sex pheromone of this species, and may play a significant role in the behaviors associated with sex-pheromone attraction.
Abstract: Body scales of the silk mothAntheraea polyphemus contain an esterase which can degrade the female sex pheromone of this species. This esterase, which appears to be stabilized to the scale cuticle, is present in both sexes, but is species specific. The enzyme may play a significant role in the behaviors associated with sex-pheromone attraction, helping to filter out stimulus noise by degrading adsorbed pheromone, thus preventing adsoptive body surfaces from becoming uncontrolled pheromone sources.
TL;DR: Evidence is given that more than one chromosome is carrying genes for nematode resistance, and the use of electrophoretic screening together with a nematodes testing program is discussed.
Abstract: Hybridizations were made between beta vulgaris and three wild species of the patellares section being resistant to the best cyst nematode {heterodera schachtii). Monosomic addition lines (2 n = 19) with full nematode resistance were investigated together with wild beets by means of electrophoretical techniques. One alkaline esterase band and a complex of several acidic esterase bands were localized on the resistance-carrying B. procumbens chromosome. The alkaline esterase marker also appeared in B. patellaris addition lines. An aconitase double band was visible in two of four B. webbiana addition lines. One resistant monotelosomic addition line with a small B. procumbens fragment had lost the esterase gene. Evidence is given that more than one chromosome is carrying genes for nematode resistance. The use of electrophoretic screening together with a nematode testing program is discussed.
TL;DR: The data indicate that neutral cholesteryl esterase in arterial smooth muscle cells can be modulated by a phosphorylation-dephosphorylation system involving the cyclic AMP-dependent protein kinase-phosphoprotein phosphatase.
TL;DR: Analysis of reaction mixtures by high performance liquid chromatography demonstrated that not all isomers of indole-3-acetyl-myo-inositol were hydrolyzed at the same rate.
Abstract: [3H]Indole-3-acetyl-myo-inositol was hydrolyzed by buffered extracts of acetone powders prepared from 4 day shoots of dark grown Zea mays L. seedlings. The hydrolytic activity was proportional to the amount of extract added and was linear for up to 6 hours at 37 degrees C. Boiled or alcohol denatured extracts were inactive. Analysis of reaction mixtures by high performance liquid chromatography demonstrated that not all isomers of indole-3-acetyl-myo-inositol were hydrolyzed at the same rate. Buffered extracts of acetone powders were prepared from coleoptiles and mesocotyls. The rates of hydrolysis observed with coleoptile extracts were greater than those observed with mesocotyl extracts. Active extracts also catalyzed the hydrolysis of esterase substrates such as alpha-naphthyl acetate and the methyl esters of indoleacetic acid and naphthyleneacetic acid. Attempts to purify the indole-3-acetyl-myo-inositol hydrolyzing activity by chromatographic procedures resulted in only slight purification with large losses of activity. Chromatography over hydroxylapatite allowed separation of two enzymically active fractions, one of which catalyzed the hydrolysis of both indole-3-acetyl-myo-inositol and esterase substrates. With the other enzymic hydrolysis of esterase substrates was readily demonstrated, but no hydrolysis of indole-3-acetyl-myo-inositol was ever detected.
TL;DR: 'Desiree' potato tubers contained about one-half the patatin of 'Kennebec', a typical commercial cultivar, but it consisted of only two major ionic forms and its ability to hydrolyse p-nitrophenyl esters was relatively low.
Abstract: 'Desiree' potato tubers contained about one-half the patatin of 'Kennebec', a typical commercial cultivar. The 'Desiree' patatin, like that of 'Kennebec', copurified with esterase activity, but it ...
TL;DR: Esterase D may be the first nonspecific esterase for which a specific biological role can be predicted and appears to be involved in the "recycling" of O-acetylated sialic acid molecules.
Abstract: The "nonspecific" esterases are a family of enzymes that were originally identified because of their reaction with synthetic O-acetyl ester substrates. While the electrophoretic polymorphisms of these enzymes have been extremely useful for genetic studies, their biological functions have remained completely unknown. Esterase D is characterized by its reactivity with 4-methylumbelliferyl acetate. This enzyme has recently been of particular interest because of its tight linkage to the putative recessive gene causing retinoblastomas, and to the recessive gene causing Wilson disease. We describe here the partial purification of a human erythrocyte esterase that appears to be highly specific for O-acetylated sialic acids. We next present evidence that suggests that esterase D is identical to this sialic acid-specific O-acetylesterase. First, both activities copurify from human erythrocyte lysates through several different purification steps, each of which use different principles of separation. Second, both activities show a remarkably similar profile of inhibition with a variety of different agents. Third, they both show a nearly identical heat-inactivation profile. This cytosolic sialic acid-specific O-acetylesterase appears to be involved in the "recycling" of O-acetylated sialic acid molecules. Thus, esterase D may be the first nonspecific esterase for which a specific biological role can be predicted.
TL;DR: Seven macrocyclic diesters analogous to hepatotoxic pyrrolizidine alkaloids have been tested in male weanling Wistar rats, and acute hepatotoxicity was dose related, and associated with the formation of pyrrolic metabolites in the liver.
TL;DR: Juvenile hormone esterase activity from the hemolymph of larvalTrichoplusia ni was analyzed by two different isoelectric focusing (IEF) methodologies and neither peak was a degradation artifact of the other caused by conditions of IEF.
Abstract: Juvenile hormone esterase (JHE) activity from the hemolymph of larvalTrichoplusia ni was analyzed by two different isoelectric focusing (IEF) methodologies. Use of techniques capable of progressively higher resolution split ultimately what appeared at lower resolution to be a single peak into two discrete peaks of JHE activity (pI 5.5 and 5.3). Neither peak was a degradation artifact of the other caused by conditions of IEF.
TL;DR: In this article, the effect of dimethyl sulfoxide (DMSO) on the enantioselectivity of pig liver esterase (EC 3.1) was studied.
TL;DR: Pig liver esterase-catalysed hydrolyses of variously substituted racemic allenic esters proceed with predictable enantiomeric selectivity, with the highest enantiomersic excess values being observed for the most highly substituted substrates.
Abstract: Pig liver esterase-catalysed hydrolyses of variously substituted racemic allenic esters proceed with predictable enantiomeric selectivity, with the highest (93%) enantiomeric excess values being observed for the most highly substituted substrates.
TL;DR: The FGH polymorphism of human red blood cells was studied in unrelated individuals, both by isoelectric focusing and starch gel electrophoresis, and with the substrates S-acetylglutathione and 4-methylumbelliferyl-acetate (the standard substrate for esterase D).
Abstract: The S-formylglutathione hydrolase (FGH) polymorphism of human red blood cells was studied in unrelated individuals, both by isoelectric focusing and starch gel electrophoresis, and with the substrates S-acetylglutathione and 4-methylumbelliferyl-acetate (the standard substrate for esterase D (ESD)). With both separation techniques the two substrates consistently gave similar and identically located zymograms. Thus, FGH (E.C.3.1.2.12) appears to be identical to ESD (E.C.3.1.1.1).
TL;DR: Three enzymes exhibiting peptidyl-L-amino acid hydrolase and esterase activities have been purified by immobilized metal-ion affinity chromatography and ion-exchange chromatography, suggesting the presence of a histidyl residue in their active sites.