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PubMed2005

New thermophilic and thermostable esterase with sequence similarity to the hormone-sensitive lipase family, cloned from a metagenomic library.

A gene coding for a thermostable esterase was isolated by functional screening of Escherichia coli cells that had been transformed with fosmid environmental DNA libraries constructed with metagenomes from thermal environmental samples. The gene conferring esterase activity on E. coli grown on tributyrin agar was composed of 936 bp, corresponding to 311 amino acid residues with a molecular mass of 34 kDa. The enzyme showed significant amino acid similarity (64%) to the enzyme from a hyperthermophilic archaeon, Pyrobaculum calidifontis. An amino acid sequence comparison with other esterases and lipases revealed that the enzyme should be classified as a new member of the hormone-sensitive lipase family. The recombinant esterase that was overexpressed and purified from E. coli was active above 30 degrees C up to 95 degrees C and had a high thermal stability. It displayed a high degree of activity in a pH range of 5.5 to 7.5, with an optimal pH of approximately 6.0. The best substrate for the enzyme among the p-nitrophenyl esters (C(4) to C(16)) examined was p-nitrophenyl caproate (C(6)), and no lipolytic activity was observed with esters containing an acyl chain length of longer than 10 carbon atoms, indicating that the enzyme is an esterase and not a lipase.

Amino Acid Sequence↗
PubMed2006

Alicyclobacillus acidocaldarius thermophilic esterase EST2's activity in milk and cheese models.

The aim of this work was to investigate the behavior of thermophilic esterase EST2 from Alicyclobacillus acidocaldarius in milk and cheese models. The pure enzyme was used to compare the EST2 hydrolytic activity to the activity of endogenous esterase EstA from Lactococcus lactis. The results indicate that EST2 exhibits 30-fold-higher esterase activity than EstA. As EstA has thioesterase activity, EST2 was assayed for this activity under the optimal conditions determined for EstA (namely, 30 degrees C and pH 7.5). Although it is a thermophilic enzyme, EST2 exhibited eightfold-higher thioesterase activity than EstA with S-methyl thiobutanoate. The abilities of EST2 and EstA to synthesize short-chain fatty acid esters were compared. Two methods were developed to do this. In the first method a spectrophotometric assay was used to monitor the synthesis of esters by the pure enzymes using p-nitrophenol as the alcohol substrate. The synthetic activities were also evaluated under conditions that mimicked those present in milk and/or cheese. The second method involved evaluation of the synthetic abilities of the enzymes when they were directly added to a model cheese matrix. Substantial ester synthesis by EST2 was observed under both conditions. Finally, esterase and thioesterase activities were evaluated in milk using the purified EST2 enzyme and in the model cheese matrix using a strain of L. lactis NZ9000 harboring the EST2 gene and thus overproducing EST2. Both the esterase and thioesterase activities measured in milk and in the cheese matrix were much greater than the activities of the controls.

Animals↗
PubMed1992

Identification of a protein-binding sequence involved in expression of an esterase gene from Streptomyces scabies.

Expression of an esterase gene from Streptomyces scabies is regulated by zinc in both Streptomyces scabies and Streptomyces lividans. A specific protein-binding site was identified on an esterase promoter fragment by using an S-30 extract from S. scabies. The location of the protein-binding site was determined by gel shift assays of promoter deletion fragments and by DNase I footprinting analysis. The protein-binding site maps from nucleotides -59 to -81 relative to the start of transcription. An esterase gene construct cloned and expressed in S. lividans was used to assess the importance of the protein-binding site. Deletion of the 23-bp protein-binding site resulted in a 10-fold decrease in esterase production when cells were grown in zinc-inducing conditions. The protein-binding site may represent a region involved in positive regulation of the S. scabies esterase gene.

Amino Acid Sequence↗
PubMed1985

Histochemical demonstration of chymotrypsin like serine esterases in mucosal mast cells in four species including man.

Serine esterases were detected in the granules of mucosal mast cells from rat, mouse, sheep, and man. Successful demonstration of enzyme activity required brief fixation (6 h) of tissues in 4% paraformaldehyde. Staining with naphthol AS-D chloroacetate produced an intense red reaction product in intraepithelial mucosal mast cells (globule leucocytes) and mucosal mast cells within the lamina propria of the gastrointestinal tract. The mast cell identity of cells stained for esterase was confirmed by sequential staining with toluidine blue (pH 0.5). Furthermore, the numbers of cells detected after staining for esterases or with toluidine blue were highly correlated. Esterase activity within mucosal mast cells/globule leucocytes from all species was inhibited with the serine enzyme inhibitor phenylmethylsulphonyl fluoride. Further histochemical studies with the substrate, N-acetyl-DL-phenylalanine B-naphthyl ester, indicated that mucosal mast cells and globule leucocytes contain esterases which are chymotrypsin like in substrate specificity.

Animals↗
PubMed1995

Organophosphates and monocyte esterase deficiency.

AIMS: To examine the possibility that monocyte esterase deficiency (MED) could be caused by exposure to organophosphates. METHODS: Pseudocholinesterase, paraoxonase and arylesterase activities were measured in the serum and acetylcholinesterase activity was measured in the red cells of a group of monocyte esterase deficient subjects and compared with the enzyme activities of a control group of monocyte esterase positive subjects. RESULTS: No significant difference was found between the enzyme activities of the monocyte esterase deficient group and the control group for any of the esterases investigated. CONCLUSION: Current or recent exposure to organophosphorus is not the cause of MED.

Acetylcholinesterase↗
PubMed2004

An esterase gene from Lactobacillus casei cotranscribed with genes encoding a phosphoenolpyruvate:sugar phosphotransferase system and regulated by a LevR-like activator and sigma54 factor.

A new esterase-encoding gene was found in the draft genome sequence of Lactobacillus casei BL23 (CECT5275). It is located in an operon together with genes encoding the EIIA, EIIB, EIIC, and EIID proteins of a mannose class phosphoenolpyruvate:sugar phosphotransferase system. After overproduction in Escherichia coli and purification, the esterase could hydrolyze acetyl sugars, hence the operon was named esu for esterase-sugar uptake genes. Upstream of the genes encoding the EII components (esuABCD) and the esterase (esuE), two genes transcribed in the opposite sense were found which encode a Bacillus subtilis LevR-like transcriptional activator (esuR) and a sigma54-like transcriptional factor (rpoN). As compared with the wild-type strain, elevated fructose phosphorylation was detected in L. casei mutants constitutively expressing the esu operon. However, none of the many sugars tested could induce the esu operon. The fact that EsuE exhibits esterase activity on acetyl sugars suggests that this operon could be involved in the uptake and metabolism of esterified sugars. Expression of the esu operon is similar to that of the B. subtilis lev operon: it contains a -12,-24 consensus promoter typical of sigma54-regulated genes, and EsuR and RpoN are essential for its transcription which is negatively regulated by EIIB(Esu). The esuABCDE transcription unit represents the first sigma54-regulated operon in lactobacilli. Furthermore, replacement of His852 in the phosphoenolpyruvate:sugar phosphotransferase system regulation domain II of EsuR with Ala indicated that the transcription activator function of EsuR is inhibited by EIIB(Esu)-mediated phosphorylation at His852.

DNA-Binding Proteins↗
PubMed1990

Characterization of nonspecific esterase activity in macrophages and intestinal epithelium of the rat.

We determined the histochemical characteristics of nonspecific esterase in different populations of rat macrophages. The cells included alveolar and peritoneal macrophages recovered by lavage and a mixed cell population obtained by collagenase digestion of the small intestine. The histochemically localized enzyme activity of alveolar and peritoneal macrophages was cytoplasmic, diffuse, and inhibited by sodium fluoride. Both populations were effectively stained using alpha-naphthyl acetate and alpha-naphthyl butyrate as the esterase substrate. When the intestinal cells were examined for activity, a greater percentage of cells showed positive nonspecific esterase than would be predicted by differential counts for macrophages on the basis of morphological criteria. We confirmed, using cell smears and tissue sections, that rat intestinal epithelial cells, a prominent component of the isolated cell population, possessed esterases that react similarly to macrophage esterases with histochemical procedures.

Animals↗
PubMed2005

Probing stereoselective inhibition of the acyl binding site of cholesterol esterase with four diastereomers of 2'-N-alpha-methylbenzylcarbamyl-1, 1'-bi-2-naphthol.

BACKGROUND: Recently there has been increased interest in pancreatic cholesterol esterase due to correlation between enzymatic activity in vivo and absorption of dietary cholesterol. Cholesterol esterase plays a role in digestive lipid absorption in the upper intestinal tract, though its role in cholesterol absorption in particular is controversial. Serine lipases, acetylcholinesterase, butyrylcholinesterase, and cholesterol esterase belong to a large family of proteins called the alpha/beta-hydrolase fold, and they share the same catalytic machinery as serine proteases in that they have an active site serine residue which, with a histidine and an aspartic or glutamic acid, forms a catalytic triad. The aim of this work is to study the stereoselectivity of the acyl chain binding site of the enzyme for four diastereomers of an inhibitor. RESULTS: Four diastereomers of 2'-N-alpha-methylbenzylcarbamyl-1, 1'-bi-2-naphthol (1) are synthesized from the condensation of R-(+)- or S-(-)-1, 1'-bi-2-naphthanol with R-(+)- or S-(-)-alpha-methylbenzyl isocyanate in the presence of a catalytic amount of pyridine in CH2Cl2. The [alpha]25D values for (1R, alphaR)-1, (1R, alphaS)-1, (1S, alphaR)-1, and (1S, alphaS)-1 are +40, +21, -21, and -41 degrees, respectively. All four diastereomers of inhibitors are characterized as pseudo substrate inhibitors of pancreatic cholesterol esterase. Values of the inhibition constant (Ki), the carbamylation constant (k2), and the bimolecular rate constant (ki) for these four diastereomeric inhibitors are investigated. The inhibitory potencies for these four diastereomers are in the descending order of (1R, alphaR)-1, (1R, alphaS)-1, (1S, alphaR)-1, and (1S, alphaS)-1. The k2 values for these four diastereomers are about the same. The enzyme stereoselectivity for the 1, 1'-bi-2-naphthyl moiety of the inhibitors (R > S, ca. 10 times) is the same as that for 2'-N-butylcarbamyl-1, 1'-bi-2-naphthol (2). The enzyme stereoselectivity for the alpha-methylbenzylcarbamyl moiety of the inhibitors is also R > S (2-3 times) due to the constraints in the acyl binding site. CONCLUSION: We are the first to report that the acyl chain binding site of cholesterol esterase shows stereoselectivity for the four diastereomers of 1.

Animals↗
PubMed1984

Bile salt-stimulated lipase and esterase activity in human milk after collection, storage, and heating: nutritional implications.

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

Bile Acids and Salts↗
PubMedDate not supplied

Different expression of esterase variants in rat hepatic and hepatoma-derived cell lines detected by electrophoresis.

Esterases in nine rat hepatic and hepatoma-derived cell lines and normal rat liver homogenate were detected by polyacrylamide gel electrophoresis coupled with active staining with alpha-naphthyl acetate or butyrate as a substrate. The esterase band patterns of the non-cancerous and oncogene-transformed cell lines were alike, but different from those of hepatoma cell lines and normal rat liver homogenate. The former groups of cells might have completely lost the characteristics of rat liver parenchymal cells, or else they might have their origin at cells other than liver parenchyma. The esterase patterns of the hepatoma cell lines (e.g., McA-RH7777) and the normal rat liver highly resembled with each other, exemplifying the slight biochemical deviation of cancer from normal cells. However, two-dimensional electrophoretogram for the McA-RH7777 cell line showed a prominent esterase spot (pI 6.0-M(r) 110 kDa) that was lacking in the normal liver. This result indicates that there is invariably some change in esterase expression between the cancer cells and the normal liver cells.

Animals↗
PubMed2000

Evaluation of horn flies (Diptera: Muscidae) from a pyrethroid susceptible colony for general and permethrin esterase activities.

In this study we describe a nonradioactive single-fly microassay for permethrin hydrolysis. We used this assay with a microplate assay for general esterase activity to evaluate the permethrin hydrolyzing and general esterase activities of aging pyrethroid-susceptible male and female horn flies, Haematobia irritans (L.). We found substantial gender- and age-related differences regarding general esterase activity, permethrin sensitivity, and permethrin hydrolyzing activity within the colony. Extracts of female flies collected 48 h after receiving their first blood meal yielded significantly greater esterase activity than male extracts. Aging female flies were more tolerant of permethrin than were male flies. In addition, a positive correlation was found to exist between the general esterase activity of aging females and their ability to hydrolyze permethrin.

Age Factors↗
PubMed2003

Characterization of general esterases from methyl parathion-resistant and -susceptible populations of western corn rootworm (Coleoptera: Chrysomelidae).

A consistent correlation between elevated esterase activity and methyl parathion resistance among Nebraska western corn rootworm, Diabrotica virgifera virgifera LeConte, populations has previously been documented. Characterization of general esterase activity using naphtholic esters as model substrates indicated that differences between resistant and susceptible strains could be maximized by optimizing assay conditions. The optimal conditions identified here were similar to those reported for other insect species. The majority of general esterase activity was found in the cytosolic fractions of resistant populations, whereas the activity was more evenly distributed between cytosolic and mitochondrial/nuclear fractions in the susceptible population. General esterase activity was predominately located in the adult thorax and abdomen. Although there were significant differences in general esterase activities between resistant and susceptible populations, the differences exhibited in single beetle activity assays did not provide sufficient discrimination to identify resistant individuals. In contrast, single larva activity assays provided greater discrimination and could be considered as an alternative to traditional bioassay techniques.

Animals↗
PubMed2001

Intact intestinal mRNAs and intestinal epithelial cell esterase, but not Cryptosporidium parvum, reach mesenteric lymph nodes of infected mice.

Dendritic cells from the mesenteric lymph nodes (MLN) contain dense esterase-positive inclusions that may originate in effete intestinal epithelial cells and reach MLN without degradation. The MLN esterases have the electrophoretic mobilities of both intestinal and mononuclear cells. Cryptosporidium parvum (CP)-infected mice have CP Ag-positive cells in MLN and also increased numbers of dense esterase-positive cells, but the CP Ag-positive cells do not stain for esterase. To characterize the handling of epithelial cell products by dendritic cells, we analyzed mRNAs in the MLN of control and CP-infected recombination-activating gene(-/-)DO11.10 mice by oligoarrays. mRNAs for 115 proteins were increased in MLN after CP infection, of which the principal increases in trypsin and chymotrypsin approximated to 250-fold. Colipase, reg-1, C-reactive protein-ductin, and amyloid were also up-regulated >10-fold and all returned to baseline by 28 days after infection. mRNAs for the same proteins were detected in intestinal epithelial cells of infected mice by oligoarrays and RT-PCR after infection. mRNA for CP beta-tubulin was detectable in intestinal epithelial cells between 5 and 18 days after infection but was not detected in the MLN throughout the observation period. It appears that host response to CP infection includes expression of mRNA for some pancreatic enzymes by intestinal epithelial cells and their subsequent transport to the MLN. The esterase and trypsin, and mRNAs for chymotrypsin, colipase, and others that may derive from uninfected epithelial cells, appear to be transported to the MLN intact, while mRNA for CP beta-tubulin that is derived from infected cells is degraded.

Animals↗
PubMed1975

Sequence of expression of paternal and maternal esterases in the ontogeny of Drosophila virilis.

The order of appearance of the parental fractions of the enzyme in ontogeny was investigated in hybrids between laboratory strains of Drosophila virilis differing in the electrophoretic mobility of certain esterases. Activity of the esterases was shown to persist at a low level during most of embryogenesis and to increase toward its end, especially after emergence. At the 16th-20th hour of embryonic development the maternal fractions are accompanied by the manifestation of paternal fractions of the slowly migrating esterase-4. Paternal forms of fast-migrating esterases (esterases-2 and -6) are found only after emergence in age I larvae.

Animals↗
PubMed1975

Acid esterase in the aorta of the hyperlipidemic rat: a histochemical study.

In rats maintained for about three weeks on a diet inducing hyperlipidemia E-600 resistant acid esterase activities were markedly reduced in the aorta in comparison with untreated animals. In rats which were maintained on an ordinary diet containing the same amount of thiouracil as given to the hyperlipidemic animals, only a slight reduction of acid esterase activities was noted. Another group of animals was fed an ordinary diet for three weeks after three weeks on a hyperlipidemic diet. In the aorta of these animals the acid esterase activities were almost normal. There was little fat deposition in the aortas of animals given the various diets. No such effects on esterase activities were observed in the liver and lung of animals of the various groups. Inhibition of acid esterase activity was also observed in rats kept on a hyperlipidemic diet for 65 days. In these animals patchy deposition of partly anisotropic lipid was observed in the intima and media.

Acid Phosphatase↗
PubMed1991

Subcellular localization of perforin and serine esterase in lymphokine-activated killer cells and cytotoxic T cells by immunogold labeling.

CTL, NK cells, and lymphokine-activated killer (LAK) cells are cytolytic lymphocytes known to produce a pore-forming protein, named perforin or cytolysin, that lyses target cells by forming large pores on the plasma membrane of the target cell. Other proteins besides perforin are found in the cytoplasmic granules of effector lymphocytes, and these include a family of serine esterases. Ultrastructural immunogold labeling studies with antibodies against perforin and a serine esterase (MTSP-1, also known as granzyme A and SE-1) show that all the granules of LAK cells and a CTL cell line contain perforin and serine esterase. For both LAK cells and CTL, perforin has been located mostly in the fine granular matrix of the granules, whereas gold particles corresponding to serine esterase have been found in both the matrix and the cap regions of the granules. Results from double immunogold labeling indicate that perforin and serine esterase colocalize to the same granules.

Animals↗
PubMed1990

Relationship between lipase and esterase.

There are at least two sites on the lipase which are concerned with catalysis: the catalytic site and the hydrophobic recognition site (lipid-binding site). The recognition site may be destroyed by mild proteolytic digestion, but the catalytic site may not be changed by this treatment. Mild treatment with trypsin caused change in the catalytic properties of hepatic triglyceride lipase; the water-insoluble ester-hydrolyzing activity of hepatic triglyceride lipase decreased, whereas the water-soluble ester-hydrolyzing activity did not change. After proteolytic digestion, hepatic triglyceride lipase resembles esterase since it hydrolyzes the water-soluble substrate better than the water-insoluble substrate. Conversely, esterase was converted to lipase by treatment with phospholipid. Cardiolipin in a concentration-dependent fashion enhanced triolein-hydrolysis of human serum carboxylesterase and this effect was associated with a dose-dependent decrease in water-soluble tributyrin hydrolysis. Based on these results, we propose the hypothesis that lipase and esterase have similar catalytic sites and that addition of a hydrophobic recognition site to esterase causes conversion of esterase to lipase (Fig. 9).

Animals↗
PubMedDate not supplied

[Properties of a complex of nonspecific esterases from the green oak roller moth].

A complex of nonspecific esterases of green oak roller moth is represented by of series of multiple forms including carboxyl-, acetyl-, aryl-esterase and esterase with mixed properties. Esterases characterized by different substrate specificity and belonging to different types change their activity in the insect ontogenesis. The authors have established the interaction of esterases with the secondary metabolism substances large amounts of which are concentrated in the oak leaves.

Animals↗