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At least 343 records · Page 19Linked to original sources
PubMed1991

Quantitative genetic variation of esterase activity associated with a gene amplification in Culex quinquefasciatus.

Amplification of the esterase B1 gene is responsible for insecticide resistance in the mosquito Culex quinquefasciatus. We used a mating scheme to isolate chromosomes carrying amplified esterase genes from a long-selected laboratory strain (Tem-R) to determine whether observed variation in esterase activity had a genetic basis. The amplified esterase genes segregated as a block and a possible newly arisen esterase B1 copy-number variant was found among the progeny of females which carried amplified B1 genes on only one homologue. A quantitative genetic analysis found significant genetic variation of esterase activity among families which carried different amplification-bearing chromosomes from the Tem-R strain. Esterase B1 copy-number variation among these Tem-R chromosomes is the most likely basis for the observed genetic variation in esterase activity.

Analysis of Variance↗
PubMed1983

Intramolecular group transfer is a characteristic of neurotoxic esterase and is independent of the tissue source of the enzyme. A comparison of the aging behaviour of di-isopropyl phosphorofluoridate-labelled proteins in brain, spinal cord, liver, kidney and spleen from hen and in human placenta.

Neurotoxic esterase activity was measured in homogenates of human placenta and hen brain, spinal cord, liver, kidney and spleen. The activity in liver comprised less than 20% of the Paraoxon-resistant esterases, but in the other tissues neurotoxic esterase accounted for over 50%. The same tissues were labelled with [3H]di-isopropyl phosphorofluoridate, and any isopropyl group transferred on to protein during 'aging' of the labelled enzymes (alkali-volatilizable tritium) was measured. No Paraoxon-sensitive labelled sites were found to age in this way in any tissue. In brain, the Paraoxon-resistant alkali-volatilizable-tritium-labelled sites correlated with the number of neurotoxic esterase labelled sites, indicating that 'aging' and isopropyl group transfer were 100% efficient. The site receiving the transferred isopropyl group was characterized by analysing the distribution of radiolabelled proteins on gel-filtration chromatography in the presence of SDS. In particulate preparations from each tissue, the protein-bound alkali-volatilizable tritium (transferred isopropyl group) was attached to a polypeptide of Mr 178 000. This same polypeptide also bore the isopropyl-phosphoryl group of neurotoxic esterase, indicating that aging of neurotoxic esterase is an intramolecular group transfer. The apparent turnover number for the enzyme (average 1.6 X 10(5) min-1) was approximately the same in each hen tissue, confirming that closely similar enzymes were present in brain, spinal cord, liver and spleen. The apparent turnover for the human enzyme was 1.8-fold higher than that for the hen enzyme. The concentration of the neurotoxic esterase phosphorylated subunit in brain, spinal cord, spleen, placenta and liver was 14.6, 3.8, 7.4, 3.3 and 3.8 pmol/g of tissue. The evidence indicated that neurotoxic esterase is present in each tissue except kidney, and that isopropyl group transfer on 'aging' occurs on this enzyme only. This process is an intramolecular transfer of the group within the same polypeptide.

Animals↗
PubMed1986

Purification, biochemical characterization, and biological function of human esterase D.

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.

Antibodies↗
PubMed1995

Kinetic and molecular differences in the amplified and non-amplified esterases from insecticide-resistant and susceptible Culex quinquefasciatus mosquitoes.

Two non-amplified esterases were purified from the insecticide-susceptible Pel SS strain of Culex quinquefasciatus. These were the two major esterase activity peaks in this strain. The two corresponding amplified carboxylesterases, Est alpha 2 and Est beta 2, involved in organophosphate sequestration were purified from two resistant C. quinquefasciatus strains. The Pel SS esterases were significantly less reactive with the organophosphates than those from the resistant strains. One of the Pel SS esterases was electrophoretically identical to amplified Culex Est beta 1. However, it differed kinetically, and in its nucleotide and predicted amino acid sequences from the two characterized amplified Est beta 1s, it is classified as Est beta 1(3). Restriction fragment analysis suggested Pel SS has only one Est alpha and one Est beta gene, while the resistant Pel RR has both amplified and non-amplified forms of Est alpha and Est beta. The EcoRI fragments for both Pel SS esterases were distinct from those of the amplified Est alpha 2(1), Est beta 2(1), or Est beta 1(1&2). An esterase with the same size EcoRI fragment as Est beta 1(3) was also present in Pel RR. This and restriction enzyme fragment analysis of C. quinquefasciatus field populations suggest that variability of the susceptible alleles may be lower than previously suggested. A non-amplified Est alpha with a unique EcoRI band was present in Pel RR. The previous esterase purification procedures may not have separated these amplified and non-amplified alleles. Hence, the small differences between the purified esterases from resistant strains may reflect mixtures of identical amplified alleles with different non-amplified alleles, which have significantly different k alpha values.

Animals↗
PubMed2000

A novel protein that binds juvenile hormone esterase in fat body tissue and pericardial cells of the tobacco hornworm Manduca sexta L.

Juvenile hormone esterase degrades juvenile hormone, which acts in conjunction with ecdysteroids to control gene expression in insects. Circulating juvenile hormone esterase is removed from insect blood by pericardial cells and degraded in lysosomes. In experiments designed to characterize proteins involved in the degradation of juvenile hormone esterase, a pericardial cell cDNA phage display library derived from the tobacco hornworm moth Manduca sexta L. was constructed and screened for proteins that bind juvenile hormone esterase. A 732-base pair cDNA encoding a novel 29-kDa protein (P29) was isolated. Western and Northern analyses indicated that P29 is present in both pericardial cell and fat body tissues and is expressed in each larval instar. In immunoprecipitation experiments, P29 bound injected recombinant juvenile hormone esterase taken up by pericardial cells and native M. sexta juvenile hormone esterase in fat body tissue, where the enzyme is synthesized. Binding assays showed that P29 bound juvenile hormone esterase more strongly than it did a mutant form of the enzyme with mutations that perturb lysosomal targeting. Based on these data, we propose that P29 functions in pericardial cells to facilitate lysosomal degradation of juvenile hormone esterase.

Amino Acid Sequence↗
PubMed1985

Purification and characterization of esterases D1 and D2 from human erythrocytes. Evidence that they are monomers.

Esterase D1 and esterase D2, two common esterase D (EC 3.1.1.1) isozymes, were isolated and purified from human erythrocytes. Their substrate specificity, pH profile and Km values were essentially identical. Their molecular mass was the same at 34 kDa on sodium dodecyl sulfate/polyacrylamide electrophoresis and at 27 kDa on Sephadex G-100 gel filtration. Antisera to each of the esterase D1 and esterase D2 isozymes were successfully raised in chickens; each antiserum reacted identically with both isozymes. These findings indicate that the isozymes are close to each other in structure. The fact that the molecular mass of the esterase D1 and esterase D2 isozymes computed on sodium dodecyl sulfate/polyacrylamide electrophoresis was close to that obtained on Sephadex G-100 gel filtration in non-dissociating buffer indicates that the isozymes are not dimers bound by disulfide bonds or a noncovalent force. These facts together indicate that the esterase D isozymes are monomers, contrary to the prevailing view that they are dimers.

Amino Acid Sequence↗
PubMed1990

Production, Purification, and Properties of Extracellular Carboxyl Esterases from Bacillus subtilis NRRL 365.

Bacillus subtilis NRRL 365 produced high extracellular carboxyl esterase activity in submerged culture media containing wheat bran, corn steep liquor, and salts. Supplementation of this medium with glucose reduced esterase activity to 37% of that in the unsupplemented control. Esterase activity was purified by ammonium sulfate fractionation, DEAE-Sephadex A-50 ion-exchange chromatography with sodium chloride gradient elution, and preparative polyacrylamide gel electrophoresis. The resultant purified components, esterases I and II, manifested single bands following silver staining of polyacrylamide gel electrophoresis gels and had final specific activities of 80 and 520 U/mg, respectively. Molecular weights for components I and II were 36,000 and 105,000 to 110,000, respectively. Esterases I and II both had a pH optimum of 8.0, with relative activities of 10 and 85%, respectively, at pH 9.0. K(m)s with p-nitrophenylacetate were 0.91 mM for esterase I and 0.67 mM for esterase II. In general, patterns of enzyme inhibition were similar for both components. Differences were observed in the relative activities of esterases I and II towards p-nitrophenyl esters of acetate, propionate, and butyrate; Activity ratios for components I and II were 100:94:48 and 100:36:23, respectively. The purified components did not hydrolyze long-chain triglycerides and did not manifest proteolytic activity.

Journal Article↗
PubMed1985

In vitro translation of mRNA for arginine esterase, the major secretory protein of dog prostate, and in vitro processing of the translation product.

Poly(A)+ rich RNA was isolated from prostate of adult dogs and translated in the rabbit reticulocyte lysate cell-free protein-synthesizing system. Two-dimensional gel electrophoresis of the translation products showed that a protein with a molecular weight of 31 000 was predominantly synthesized. This protein was immunoprecipitated with antibodies directed against purified arginine esterase from dog seminal plasma. mRNA isolated from the prostate of animals castrated for 1 or 2 weeks was unable to direct the synthesis of arginine esterase. However, the synthesis of the enzyme could be stimulated by androgens in castrated animals, presumably by increasing prostatic concentrations of arginine esterase mRNA. The single chain translation product could be further processed in vitro by the addition of dog pancreas microsomes and purified arginine esterase. This procedure yielded split chains of arginine esterase which had identical electrophoretic mobilities as seminal plasma enzyme by two-dimensional gel electrophoresis. When prostatic tissue slices were incubated with tunicamycin, the unglycosylated arginine esterase obtained had a lower molecular weight than the in vitro translation product, suggesting that a signal peptide had been removed in the living cells. These results indicate that arginine esterase processing may include the following steps: removal of a signal peptide, glycosylation, and splitting of the polypeptide chain by active arginine esterase in the secretory granules or outside the cell.

Animals↗
PubMed1991

[Synthesis of nonspecific esterase in small intestine enterocytes during experimental coccidiosis in suckling pigs].

The activity of nonspecific esterase (EC. 3.1.1.1.) was evaluated in the small intestine mucosa of 21 conventional piglets infected on day 5 after parturition (DAP) with oocysts of the Eimeria debliecki coccidium (infection dose of 200,000 oocysts) for this evaluation a microdensitometric analysis at the level of enterocytes was used. The same examination was also performed in the small intestine mucosa of four control conventional piglets at the age of 2-5 days (Tab. I). The synthesis of nonspecific esterase in the experimentally infected piglets was followed on day 1 to day 10 after infection (DAI). The activity of nonspecific esterase in the small intestine mucosa was found to decrease in a direction from duodenum absorption cells (D mean 34.15) to caudal ones (Fig. 1); ileum enterocytes have the optical density of the enzyme by 8.2% lower (D mean 31.38). The deposition of nonspecific esterase is localized mainly in the supranuclear zone of enterocytes while in the para- and infranuclear zones of absorption cells its concentration is only minute. In the experimentally infected piglets a marked increase in the optical density of nonspecific esterase of enterocytes was observed as soon as on day 1 after infection when the enzyme concentration increased by 19.4% (Tab. II). The maximum increase in the activity of nonspecific esterase of absorption cells was recorded on DAI 9 when the enzyme D mean value was higher by 165% in comparison with the activity of nonspecific esterase demonstrated in the control piglets (Fig. 2, 3, 4). But at the end of experimental infection (DAI 10) the total density of nonspecific esterase of enterocytes decreased by 38.2%.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Biochemical properties of blood esmolol esterase.

The blood esterase mediating the hydrolysis of esmolol was characterized in several different species including man. In contrast to most ester-containing drugs, hydrolysis of esmolol was mediated by an esterase in the cytosol of red blood cells (RBC) in man and dogs and not in plasma or RBC membrane. Species differences in the esterase activity existed. Guinea pig and rat blood esterase activities were much greater than those in the dog followed by those in man. In addition, the esterase activity in rat and guinea pig blood was localized in plasma and not in RBC. Purified human serum cholinesterase, human RBC membrane acetylcholinesterase, human hemoglobin, human carbonic anhydrases A and B, and human and dog serum albumin were all inactive against esmolol. Esmolol esterase activity in human and dog blood was inhibited by sodium fluoride, EDTA, and p-hydroxymercuribenzoate, but not by echothiophate, eserine, and acetazolamide. In contrast, echothiophate and sodium fluoride, but not eserine, inhibited the esterase activity in rat and guinea pig plasma. Metabolic interaction studies indicated that acetylcholine, succinylcholine, procaine, and chloroprocaine did not interfere with the metabolism of esmolol by human and dog blood. Based on the results, it appeared that an arylesterase in human and dog RBC cytosol mediated the hydrolysis of esmolol while an aliphatic esterase mediated the hydrolysis of esmolol in guinea pig and rat plasma.

Animals↗
PubMed1987

Biochemical and functional properties of serine esterases in acidic cytoplasmic granules of cytotoxic T lymphocytes.

Percoll gradient fractions of homogenates of murine cloned cytotoxic T lymphocytes (CTL) were analyzed for the trypsin-like enzyme alpha-N-benzyloxy-carbonyl-L-lysinethiobenzyl ester (BLT) esterase recently described in CTL homogenates. Enzymatic activity was found in three areas of the gradient: the dense cytolysin containing granules; a light granule fraction; and a variable amount in the soluble fraction at the top of the gradient. Gel filtration columns showed a major peak of BLT esterase activity eluted at the position of a 60-kDa protein, and an additional, minor BLT esterase peak eluting at about 27 kDa. The separated enzymes were both significantly inhibited by the serine protease inhibitors diisopropylfluorophosphate and phenylmethyl sulfonyl fluoride (PMSF), indicating they are both serine proteases, but showed different patterns of inhibition by a series of inhibitors, suggesting the larger enzyme is not a simple dimer of the smaller. pH activity profiles of both CTL BLT esterases showed an optimum at about pH 8. PMSF inactivation of BLT esterase in detergent extracts of CTL diminished sharply as the pH was dropped below 7. Agents which raise the pH of acidic intracellular compartments were found to markedly enhance the PMSF inactivation of BLT esterase in intact CTL, showing that the granules have a low internal pH. Similarly, [3H]diisopropylfluorophosphate labeling of intact CTL gave four protein bands on non-reduced gels, of which two were labeled threefold more effectively in the presence of chloroquine. In parallel studies of inactivation of CTL lytic activity, PMSF pretreatment caused a 50% reduction of the lytic activity under conditions where greater than 90% of the BLT esterase activity was inactivated. Addition of agents raising the intragranular pH dramatically enhanced the BLT esterase inactivation but did not concomitantly reduce CTL lytic activity. These results indicate that inactivation of lytic function by PMSF is unlikely to be due to its reaction with protease in acidic granules, and suggest that the activity of these enzymes may not be required for cytotoxicity.

Animals↗
PubMed1994

Molecular characterization and cloning of an esterase which inactivates the macrolide toxin brefeldin A.

The macrolide antibiotic brefeldin A (BFA) was described as a phytotoxin and pathogenicity factor from Alternaria carthami Chowdhury, the causal agent of a devastating blight disease in safflower (Carthamus tinctorius L.). The toxin is known to inhibit the endoplasmic reticulum-Golgi flux and processing. Conventional breeding of safflower for resistance to the Alternaria blight disease has failed, and in situ detoxification of brefeldin A is a novel approach for the protection of field-grown safflower plants from the blight disease. As a first step towards this goal, a strain of Bacillus subtilis has been isolated which is capable of hydrolyzing brefeldin A to a non-toxic metabolite, brefeldin A acid. The BFA esterase was purified to homogeneity from B. subtilis extracts and shown to consist of a monomeric peptide of approximately 40 kDa. Besides brefeldin A, the esterase hydrolyzed ethyl valerate, which structurally resembles the lactone portion in the brefeldin A molecule, but failed to accept other macrolides such as erythromycin or zearalenone. Roughly 12% of the esterase sequence was identified by microsequencing tryptic peptides and the N terminus, which lacked a methionine leader residue. Corresponding oligonucleotide probes were employed to clone the esterase gene in pUC18. One of seven clones was sequenced and shown to code for the full size esterase protein of 372 amino acid residues. The esterase gene was subcloned in pT7-7 and expressed in Escherichia coli yielding a fusion protein with a specific esterase activity 3-fold over that of the enzyme purified from B. subtilis. The cloned esterase provides the basis for the generation of transgenic safflower plants as a valuable asset in the research on nonspecific phytotoxins and in supporting breeding for Alternaria blight resistance.

Amino Acid Sequence↗
PubMed1997

Esterase gene amplification in Culex pipiens.

In the mosquito Culex pipiens one of the major resistance mechanisms to organophosphorous pesticides (OPs) is increased detoxification of insecticide. This resistance is the consequence of overproduction of two types of esterases, esterases A and B, coded at two loci, Est-3 (A esterase) and Est-2 (B esterase). We have analysed the genomic structure of these genes in different strains resistant to OPs and have attempted to characterize the different types of mutations leading to the resistant phenotypes. It is shown that, concerning the more frequent resistant phenotypes, mutations leading to resistance are of two main types. First, overproduction of one A esterase present in Southern France results from a regulatory mechanism. The second type of mutation is gene amplification which involves events that have initially generated the duplication of both the A and B esterase or only the B esterase locus. We report the point that the most frequent esterase overproductions are the results of eight different mutations and that, given the range of distribution of these genotypes, mutation leading to an efficient resistance gene is one of the most limiting factors for the evolution toward resistance in Culex pipiens.

Animals↗
PubMed1957

Some properties of an esterase derived from preparations of the first component of complement.

Studies on an esterase derived from partially purified preparations of the first component of complement are described. The esterase hydrolyzed certain synthetic amino acid esters, among which N-acetyl-L-tyrosine ethyl ester was most susceptible. This was hydrolyzed maximally between pH 7.5 and 8.2, and at 41 degrees C. The esterase could not be identified with other previously described hydrolytic enzymes. An esterase with similar properties could also be eluted from antigen-antibody aggregates which had been treated with serum. Human serum contained a heat-labile inhibitor of the esterase which could not be identified with any of the known components of complement. The esterase was also inhibited by certain reducing agents. The experiments described support the early hypothesis that complement exerts its action enzymatically, but the physiological role of the esterase derived from preparations of complement is not yet clear.

Amino Acids↗
PubMed1977

Esterase reactions in acute myelomonocytic leukemia.

Specific and nonspecific esterase reactions of bone marrow cells from 14 patients with untreated acute myelomonocytic leukemia and six patients with acute histiomonocytic leukemia were examined. The technic for esterase determination permitted simultaneous visualization of both esterases on the same glass coverslip containing the marrow cells. In cases of acute histiomonocytic leukemia, monocytes, monocytoid hemohistioblasts and undifferentiated blasts stained intensely positive for nonspecific esterase, using alpha-naphthyl acetate as the substrate. No evidence of specific esterase activity using naphthol ASD-chloroacetate as the substrate and fast blue BBN as the dye coupler was apparent in these cells. In all of the cases of acute myelomonocytic leukemia, both specific and nonspecific esterases were visualized within monocytes, monocytoid cells, and granulocytic cells that had monocytoid-type nuclei. Nonspecific esterase activity was not observed in polymorphonuclear leukocytes in cases of myelomonocytic leukemia. The results support a current viewpoint that acute myelomonocytic leukemia may be a variant of acute myeloblastic leukemia, and that cytochemically, many of the leukemic cells in myelomonocytic leukemia share properties of both granulocytes and monocytes.

Acute Disease↗
PubMed1986

Comparative esterase electrophoretic polymorphism of Escherichia coli isolates obtained from animal and human sources.

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.

Animals↗
PubMed1998

A novel esterase from Saccharomyces carlsbergensis, a possible function for the yeast TIP1 gene.

An extracellular esterase was isolated from the brewer's yeast, Saccharomyces carlsbergensis. Inhibition by diisopropyl fluorophosphate shows that the enzyme has a serine active site. By mass spectrometry, the molecular weight of the enzyme was 16.9 kDa. The optimal pH for activity was in the range of four to five. Esterase activity was found in beer before pasteurization, and a low level of activity was still present after pasteurization. Caprylic acid, which is present in beer, competitively inhibited the esterase. The substrate preference towards esters of p-nitrophenol indicated that the enzyme prefers esters of fatty acids from four to 16 carbon atoms. The esterase has lipolytical activity; olive oil (C-18:1), which is a classical substrate for lipase, was hydrolysed. N-terminal sequence analysis of the esterase yielded a sequence which was identical to the deduced amino acid sequence of the S. cerevisiae TIP1 gene. The esterase preparation did not appear to contain significant amounts of other proteins than Tip1p, indicating that the TIP1 gene is the structural gene for the esterase.

Amino Acid Sequence↗
PubMed1977

A histochemical study of aldehyde fuchsin-positive material and "high-esterase cells" in the pineal gland of the Mongolian gerbil.

The pineal gland of the Mongolian gerbil consists of a superficial gland, stalk and deep pineal. The deep pineal differentiates postnatally. Histochemical studies of the superficial pineal gland indicate that it may be involved in the secretion of protein. Presumptive secretory material visualized by aldehyde fuchsin (AF) and chrome hematoxylin was observed along the course of blood vessels and among the pinealocytes. The distribution and texture of the AF-positive material was distinctive. It did not correspond to the pattern and texture of material stained with PAS, Sudan Black or acid orcein. Staining with AF was markedly reduced after incubation with trypsin, indicating that the AF-positive material is at least partially protein. The amount of stainable material increased with age. The AF-positive material was observed in what appeared to be interstitial or glial cells and processes, and in the processes of perivascular cells. Cells and fibrous processes with high non-specific esterase activity ("high-esterase cells") were observed among the pinealocytes and along the course of blood vessels. The distribution of the "high-esterase cells" and the morphology and texture of their esterase-containing processes were remarkably similar to the morphology and distribution of the material that stained with AF. It may be that the "high-esterase cells" contain AF-positive material. The "high-esterase cells" hydrolyzed both alpha-naphthyl acetate and alpha-naphthyl butyrate. The pinealocytes hydrolyzed only alpha-naphthyl acetate. The "high-esterase cells" appear to form a distinct class of cells within the superficial pineal gland. They are tentatively identified as a type of glial cell.

Acid Phosphatase↗