Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ESTERASES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,243 records · Page 69Linked to original sources
PubMed1998

Esterase activity and release of ethyl esters of medium-chain fatty acids by Saccharomyces cerevisiae during anaerobic growth.

During anaerobic fermentation, Saccharomyces cerevisiae releases large amounts of medium-chain fatty acids (MCFAs) and related ethyl esters which are very important for aromatic quality of fermented beverages. The physiological function of ester synthesis is not yet understood. As MCFAs are toxic, their conversion to esters has been proposed to be a detoxification mechanism. Esterases possess ester synthesizing ability. Throughout an anaerobic fermentation of a lipid-free synthetic medium carried out with a S. cerevisiae strain selected for wine making, we have monitored MCFA and ethyl ester production and, at the same time, measured growth and esterasic activity of intact cells. Because no correlation was found between the concentration of each fatty acid and its ethyl ester, there is no evidence that ester synthesis reduces the toxicity of MCFAs. Esterasic activity did not show any correlation with ester synthesis, but it was related to the release of MCFAs. A model is proposed in which ester synthesis is a consequence of the arrest of lipid biosynthesis resulting from a lack of oxygen. Under these conditions, an excess of acyl coenzyme A is produced, and acyl esters are formed as secondary products of reactions aimed at recovering free coenzyme A.

Anaerobiosis↗
PubMed1998

Esterase patterns and phylogenetic relationships of species and strains included in the Drosophila buzzatii cluster.

Ten strains of two species in the Drosophila buzzatii cluster (D. serido and D. seriema) were examined as to esterase patterns using polyacrylamide gel electrophoresis. The migration rate of esterases, and their substrate specificity to alpha and beta naphthyl acetates, were analysed. Other esterase features such as inhibition behaviour, presence in males and females and location in the head, thorax or abdomen of flies, were also examined. The present data, together with results obtained by others for eight strains of D. koepferae, D. serido, D. seriema and D. buzzatii, show that 69 bands have been detected in the eighteen strains studied. This total number of bands was used for comparison of strains and species by similarity index, analysis of dependence and cluster analysis. The comparisons confirmed the existence of a high degree of similarity among D. seriema strains and among D. koepferae strains, but indicated differentiation among the D. serido strains. Two strains (D69R2 and D69R5) which differed from the others of the latter species, showed closer affinities with D. buzzatii, which indicates the need for further work on those strains classified as D. serido.

Animals↗
PubMed1999

Prostaglandin E1 influences serum cholesterol esterase and lipase activity in different ways.

The in vitro and in vivo effects of prostaglandin E1 on cholesterol ester hydrolase (CEase) and lipase [glycerol ester hydrolase (GEH)] activity in human serum were examined. Cholesterol esterase and lipase activity in the sera of men with atherosclerosis differed substantially from that in the control subjects. CEase activity was raised and GEH activity suppressed in the serum of men with atherosclerosis compared with controls. Prostaglandin E1 in vitro was found to suppress lipase but to increase cholesterol esterase activity to some extent. However, in vivo activities of GEH and CEase in the sera of men with chronic arterial occlusions of the lower limbs treated with prostaglandin E1 revealed that lipase activity was increased but that cholesterol esterase activity was unchanged. Recent studies have demonstrated that by altering the metabolic pathways of acylcholesterols and triacylglycerols, prostaglandin E1 may lead to the development of new strategies for retarding atherosclerosis.

Adult↗
PubMedDate not supplied

Comparison of the role of esterases in the differential age-related sensitivity to chlorpyrifos and methamidophos.

More than 30 years ago, scientists recognized that, at a given dosage, the young rat was more sensitive than the adult to the toxicity of many organophosphorus, anticholinesterase pesticides. This observation went basically unexamined until recently. Renewed interest has emerged in scrutinizing this age-related sensitivity to pesticides, especially in light of the many new pesticides which are currently marketed. Our laboratory has been involved in comparing the age-related sensitivity of young and adult rats to chlorpyrifos [Dursban, Lorsban; O,O-diethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate] and methamidophos (Monitor; O,S-dimethyl phosphoamidothioate). Using chlorpyrifos, there is marked age-related sensitivity: direct oral dosing of the preweanling rat (postnatal day 17; PND17) with chlorpyrifos causes a toxic response (defined either behaviorally or biochemically) at a approximately 5-fold lower dosage than in adults (oral, maximum tolerated dose for the PND17 is 20 mg/kg versus 100 mg/kg for the adult). Other studies have indicated that the rat detoxifies chlorpyrifos and its oxon by binding to carboxylesterases and hydrolysis by A-esterases. The young rat is deficient in both these detoxification enzymes, which may explain the increased sensitivity of the young to chlorpyrifos toxicity. The age-related pattern for methamidophos is distinctly different: the oral, maximum tolerated dose is the same (8 mg/kg) whether the animal is 17 days old or an adult. We present data which indicate that methamidophos is not detoxified appreciably either in vivo or in vitro by A-esterases or carboxylesterases. Therefore, we submit the following hypothesis: organophosphorus pesticides, like chlorpyrifos, which are detoxified via A-esterases or carboxylesterases are more likely to exhibit age-related differences in sensitivity than pesticides which are not detoxified via these routes.

Acetylcholinesterase↗
PubMed1976

The requirement for esterase activation in the anti-immunoglobulin-triggered movement of B lymphocytes.

In this paper we bring evidence suggesting that there is activation of an esterase upon reaction of anti-immunoglobulin antibodies (anti-Ig) with murine B lymphocytes. B lymphocytes upon exposure to anti-Ig cap the ligand-receptor complexes and immediately afterward become briefly motile. It is this latter step which is inhibitable by exposure to di-isopropyl phosphofluoridate (DFP). Various experimental manipulations indicated that treatment with anti-Ig activates the cell for motility which, however, is not manifested until the temperature is raised to 37 degrees C. The cell incubated with anti-Ig at cold temperatures becomes susceptible to the effect of DFP, suggesting that the antibody-treated cells are activated up to but not beyond the DFP inhibitable step. Exposure of cells to DFP and removal of it before their treatment with anti-Ig does not affect the anti-Ig-induced response. Four lines of evidence indicate that the reduction of lymphocyte movement of DFP is due to the inhibition of an esterase activated by the combination of antibody and cell: 1) The inhibition by DFP is irreversible; once DFP has reacted it can be washed away and the antibody-treated cell is still inhibited. 2) The inhibition increases with time of contact of lymphocytes and DFP and with the concentration of DFP. 3) A very poorly phosphorylating phosphonate, phenyl ethyl pentylphosphonate is completely inactive under conditions where an excellent phosphorylating phosphonate, p nitrophenyl ethyl pentylphosphonate maximally inactivated the cells' movement. 4) The amino acid esters, tosyl L arginine methyl ester and benzoyl arginine methyl ester specifically prevent the inactivation by DFP. The last finding suggests that tosyl L arginine methyl ester and benzoyl L arginine methyl ester might be substrates for the putative antibody-induced lymphocyte esterase. Lymphocytes incubated with antibody in the cold for more than 30 min lose their ability to move when the temperature is raised, suggesting that there is a time-dependent deactivation of the cell.

Amino Acids↗
PubMed1975

Enhancement of migration inhibitory factor activity by plasma esterase inhibitors.

The plasma esterase inhibitors alpha2-macroglobulin, alpha1-antitrypsin, C1-inhibitor, antithrombin-heparin cofactor, and, as previously described, soybean trypsin inhibitor (Kunitz) and diisopropylphosphorofluoridate (9) enhance the response of guinea pig macrophages to migration inhibitory factor. To obtain this effect, macrophages are incubated with inhibitors prior to assay. The data suggest that (a) the enhancement of migration inhibitory factor response is due to the inhibition of esterases associated with the macrophage through a distinct active site on the inhibitors, and (b) that the active sites of antithrombin-heparin cofactor and soybean trypsin inhibitor, which interact with the macrophage enzymes, are different from the active sites of these inhibitors which interact with thrombin and trypsin respectively. Chemical modification of the active site of antithrombin-heparin cofactor for thrombin and of soybean trypsin inhibitor for trypsin does not affect their capacity to enhance the migration inhibitory factor response. From studies with thrombin, it was known that antithrombin-heparin cofactor has a heparin binding site. Addition of heparin was found to prevent the migration inhibitory factor-enhancing effect of antithrombin-heparin cofactor. The present results suggest that plasma esterase inhibitors may play a regulatory role in the response of macrophages to mediators of cellular immunity.

Animals↗
PubMedDate not supplied

[Effect of a low-frequencey magnetic field on esterase activity and change in pH in wheat germ during swelling of wehat seeds].

The role of nonsteady phenomena determined by a low velocity of ion movements in a weak external field is considered in relation to their possible nonlinear effects on processes occurring in boundary layers near the membrane, particularly, on the release of membrane-bound proteins and pH value. It is shown that a short-term treatment of wheat seeds with low-frequency magnetic field at the stage of esterase activation during seed swelling enhances the activation of esterases; the effect observed at final stages of activation depends on the time after the treatment with electromagnetic field. Treatment of seeds with electromagnetic field at this stage changed qualitatively the time course of the release of reaction products into the medium: the reaction rate increased initially and then decreased below the control level. At earlier stages of swelling in treated seeds and at all stages in control seeds, the time course of the product release was linear. The retardation of the release of the reaction products at terminal stages of esterase activation is presumably related to the release of proteins and their complexes under the action of electromagnetic field and the resulting restoration of the barrier properties of membranes. Treatment with electromagnetic field also caused a noticeable acceleration of proton flow form the medium, which was judged from pH changes in the bulk medium and in the vicinity of germ surface. The difference between the treated and control samples after 23-24 h of imbibition became statistically significant and was as high as 0.4 pH units. By taking into account the nonsteady phenomena occurring upon action of low-frequency electromagnetic field, it is possible to explain unusual dependences of biological effects on the amplitude of the electromagnetic field, including the atypical enhancement of these effects by the action of weak low-frequency fields.

Electromagnetic Fields↗
PubMed2000

[Electrophoretic forms of glucose-6-phosphate dehydrogenase, acid phosphatase and esterase in Amoeba species amoebas].

Glucose-6-phosphate dehydrogenase (G6PD), acid phosphatase and esterases in free-living amoebae of 7 Amoeba species were investigated with the use of disc-electrophoresis in polyacrylamide gel. The evidence provided is suggestive that the electrophoretic isoenzyme patterns of acid phosphatase and esterases (and G6PD in some cases), in addition to a few morphological characters, can serve as a taxonomic criterion for species identification within this genus, as well as for revealing erroneously classified species and strains. It is suggested that A. indica is an independent species whose preliminary diagnosis has been given in this paper. It is concluded that A. discoides and A. lescherae are strains of A. proteus, rather than two independent species. A and As-102 amoebian strains, kept in the collection of protozoan strains and species of the Institute of Cytology RAS and referred to as strains of A. proteus, belong in reality to another Amoeba species and even to another genus within the family Amoebidae. This conclusion has been documented by results of our analysis of electrophoretic patterns of acid phosphatase and esterases in these strains.

Acid Phosphatase↗
PubMedDate not supplied

The activity of cholesterol esterase and ceruloplasmin are inversely related in the serum of men with atherosclerosis obliterans.

BACKGROUND: Ceruloplasmin is a copper-containing (2-glycoprotein and a member of the acute phase reactant family. Parallel changes in ceruloplasmin and copper concentration have been observed in diseases accompanied by severe inflammation, indicating a closely related process. Cholesterol esterase participates in lipoprotein degradation by the hydrolysis of cholesteryl esters in low density lipoproteins (LDL-CE). LDL-CEs are substrates for cholesterol esterase, but can also undergo oxidation by metal ions. The reduction of lipid hydroperoxides has been claimed to play a key role in the control of lipid peroxidation in living systems. MATERIAL AND METHODS: The experimental group consisted of 16 men with atherosclerosis obliterans of the lower limbs, with 12 healthy male volunteers as a control group. The activity of cholesterol esterase (CEase), ceruloplasmin (Cp), and glutathione peroxidase (GPx), and the concentrations of malonyldialdehyde (MDA) and copper were determined in serum samples. RESULTS: CEase and Cp activity and copper concentrations were found to be greater in the AO group than in the controls. In addition, CEase and Cp were negatively correlated (r=(0.65, p< or = 0.05) in the serum of men with AO, but not in the controls. Moreover, copper concentration was significantly correlated with the activity of Cp and GPx (r=0.81 and r=0.58, respectively). The reduced GPx activity and the higher MDA concentration found in the AO group indicate a decline in the antioxidative barrier of plasma. CONCLUSIONS: The results reported here show an inverse relationship between the activities of CEase and Cp in chronic arterial occlusion of the lower limbs, which may reveal the interaction between the antioxidant and lipolytic enzymes.

Aged↗
PubMedDate not supplied

[High esterases as mechanism of resistance to organophosphate insecticides in Aedes aegypti strains].

Five strains of Aedes aegypti L. one from Cuba and 4 from Venezuela were evaluated to determine their resistance to organophosphate insecticides (temephos, chlorpiriphos and pirimiphos methyl). In the Venezuelan strains only APURE showed resistance to temephos. In TACHIRA and MIRANDA moderate resistance values were noted (FR50 5 to 10x) for chlorpiriphos and high levels of resistance (FR > 10x) to this insecticide were found in ARAGUA. All the Venezuelan strains showed high levels of resistance to pirimiphos methyl. The Cuban strain from Santiago de Cuba revealed moderate resistance to temephos and pirimiphos methyl, but high resistance to chlorpiriphos. The results of the biochemical tests proved the presence of esterase and glutathione-s-transferase at high frequency in almost every strain. By the polyacrilamide gel electrophoresis, a strongly stained band was observed in all the strains with a Rf value of 0.779; it was named esterase A4 and was not seen in the susceptible reference strain. The meaning of this esterase in the resistance to organophosphate insecticides is yet to be determined. Resistance to these insecticides in Aedes aegypti is a serious problem for the control of this species therefore integrated management strategies were proposed to prevent or delay the appearance of this species in Cuba and Venezuela.

Aedes↗
PubMedDate not supplied

[The activity and isoenzyme spectrum of esterases in erythroid and myeloid cells of rabbit bone marrow].

In erythroid and myeloid cells of rabbit bone marrow the total activity of esterases and their isozyme spectrum in polyacrylamide gel disc electrophoresis were studied. Higher esterase activity was observed in the myeloid cells as compared with erythroid ones. In the isozyme spectrum of esterases from the myeloid cells an additional cathode fraction was observed, which was not found in extracts of erythroid cells. Experiments with inhibitors showed that the enzymes studied were carboxyl- and acetylesterases.

Acetylesterase↗
PubMed2001

[A study on polymorphism of salivary esterase in personal identification].

OBJECTIVE: To research the value of polymorphism of salivary esterase(Set) in paternity and personal identification. METHODS: Phenotype and genotype of human salivary esterase were detected in 114 liquid saliva samples from the Chinese population by disc electrophoresis and fast blue RR staining assay. RESULTS: The frequency of Set type was F 22.81%, FS 50.88%, S2 6.31%. The estimated gene frequency of SetF was 0.4825 and SetS was 0.5175. The PE was 0.1875 and the DP was 0.6199. CONCLUSION: Polymorphism of salivary esterase (Set) was practical in paternity and personal identification.

Esterases↗
PubMed2001

[Cloning and sequencing of the gene encoding esterase estA from Ralstonia eutropha CH34].

An esterase-positive clone was isolated by screening a genomic library of Ralstonia eutropha CH34 constructed in Escherichia coli S17-1 with top agar containing alpha-naphtyl acetate and Fast Blue RR. A gne encoding esterase activity, estA was subcloned from this clone. Nucleotide sequencing of estA showed that it was a 825 bp open reading frame, encoding an esterase EstA, composed of 275 amino acids with a predicted molecular mass of 30,785 D. Homology analysis revealed that EstA exhibited significant amino acid similarity with the enzymes involved in the meta-cleavage pathway in the metaboleism of aromatic acid compounds.

Amino Acid Sequence↗
PubMed2001

[Inhibition of in vitro translation of esterase mRNA of dipterex-resistant mosquito (Culex pipiens pallens) by antisense nucleic acids].

OBJECTIVE: To examine the inhibitory effect of antisense nucleic acid on the in vitro translation of esterase mRNA from dipterex-resistant Culex pipiens pallens. METHODS: 18-mer nucleic acid was synthesized and complementary to the translation initiation site of mRNA of dipterex-resistant mosquitoes. The ODNs were annealed to the corresponding mRNA molecules and they were added to rabbit reticulocyte cell-free system. The translation products were analyzed by SDS-PAGE. After fixing, the gel was exposed to X-ray film by autoradiography for analysis of protein synthesis. RESULTS: Six mumol/L of ODNs elicited a 50% reduction in specific protein expression, and 20 mumol/L of ODNs inhibited the expression of esterase by 80%. The SDS-PAGE showed that the band of reduced amounts of 65 kDa protein for resistant mosquito was almost the same as that for sensitive sample. CONCLUSION: Antisense oligonucleic acids to the esterase mRNA of dipterex-resistant mosquito could effectively inhibit its in vitro translation.

Animals↗
PubMed2003

[Determination of esterase activity of Candida varieties].

This study was performed to determine the esterase activity of Candida species and to search the usefulness of tween 80 opacity test for the identification. Totally 124 Candida strains (66 C. albicans, 25 C. tropicalis, 14 C. parapsilosis, 10 C. glabrata, 3 C. krusei, 2 C. kefyr, 2 C. guilliermondii, 1 C. lusitaniae, 1 C. rugosa) isolated from various clinical specimens were included in this study. Tween 80 opacity test was applied to the strains and the plates were evaluated after incubation at 30 degrees C for ten days, by examining daily, for the presence of an opaque zone. As a result, 63 of (%95) of C. albicans, 23 of (93%) C. tropicalis, 8 of (57%) of C. parapsilosis and 1 (10%) of C. glabrata strains were found positive for esterase activity, whereas the other strains were found negative. It can be concluded that, tween 80 opacity test is a simple and economical method and may be useful as a supplementary test for the identification of Candida species, by detecting esterase activities which have arised on different days.

Candida↗
PubMed2003

[The correlation between DDVP resistance of Culex pipiens pallens and esterase activity].

OBJECTIVE: To detect the resistance index and esterase activity of each generation of DDVP-resistant Culex mosquitoes and analyze the relationship between insecticide resistance and esterase. METHODS: WHO bioassay and micro-plate measurement were used for the detection. RESULTS: The resistance index increased to 12.17 after 43 generations' insecticide selection compared to 1.00 as sensitive isolate. The nonspecific esterase(NSE) activity of the mosquitoes became strengthened with the extension of the generations, and the individual frequency of those with OD values no less than 0.9 increased gradually, consistent basically to the bioassay. The AChE average inhibition rate decreased with the extended generation and increased resistance, and the individual frequency of those with inhibition rate less than 30% became strengthened with the extension of generations, showing a positive correlation. CONCLUSION: The activity of NSE and AChE shows a correlation with DDVP resistance.

Acetylcholinesterase↗
PubMed1976

Chemo-architectonic studies in a submammalian brain. Adenosine triphosphatase and simple esterase in the diencephalon and mesencephalon.

The present report deals with the histo-enzymological mapping of adenosine triphosphatase and simple esterase in the diencephalon and mesencephalon of Uromastix hardwickii. The enzymatic make-up, in both cases, does not differ markedly in the various nuclei; few variations, of course, occur in some midbrain areas like pretectal nuclei. The latter are intensely positive for ATPase, while these nuclei are moderate to simple esterase. Nevertheless, one of the most interesting results pertaining to simple esterase activity is of a high order in the fiber tracts in comparison to ATPase. The other interesting feature relates to the fact that generally intensely positive nuclei, in ATPase preparations, are those which have extensive efferent fibres. The metabolic significance of high degree of ATPase activity vis-a-vis extensive efferent connections has been exhaustively discussed, besides the possible significance of the general data obtained.

Adenosine Triphosphatases↗
PubMed1977

Aspirin esterase of gastric mucosal origin.

The enzyme, aspirin esterase, which converts acetylsalicyclic acid to the less toxic salicyclic acid, was found to be present in gastric mucosal specimens obtained from surgically resected tissue. The enzyme was found to be stable to storage and active at two pH optima. Alcohol in the reaction mixture produced a net effect of slowing the rate of aspirin hydrolysis; this was attributable to a marked inhibitory effect on aspirin esterase activity which was not completely counteracted by the increased rate of spontaneous breakdown of aspirin by alcohol. Age, sex, or gastric disease state of the patient from whom the tissue was obtained, did not significantly alter the level of enzyme activity measured, nor were different levels obtained from body or antral mucosa. In patients with gastric ulcer, those with a previous history of regular aspirin consumption did not show significantly different levels from those without such a history. It is concluded that aspirin esterase activity of gastric mucosa is not alone a significant factor in any role acetylsalicyclic acid may play in the etiology and natural history of chronic peptic ulcer.

Age Factors↗