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PubMed1987

Pregnancy-associated esterase in sera of baboons.

Baboon serum samples were resolved by starch gel electrophoresis and polyacrylamide gradient gel electrophoresis and stained with naphthol substrates for esterase activity. An esterase that hydrolyzed alpha-naphthyl butyrate in preference to alpha-naphthyl acetate was found in very high activities in some individuals but not others. It migrated just cathodal of the albumin band in starch gels. In polyacrylamide gradient gels, it co-migrated with albumin and had an apparent molecular weight of approximately 65,000 daltons. Electrophoretic analysis by gel electrophoresis of random serum samples from male and female baboons indicated that this esterase was present only in the sera of pregnant baboons. Further investigation of serial samples collected from carefully monitored baboons confirmed that the amount of activity of this esterase was correlated with stage of pregnancy. Therefore, it was named pregnancy esterase (PE). PE was detectable by gel electrophoresis and chromogenic staining techniques as early as day 30 of pregnancy; its activity gradually increased with progressive pregnancy and reached maximum activity near full term (182 days). Soon after parturition, the activity of PE decreased rapidly and was not detected in maternal sera by day 14 postpartum. No evidence of PE was detected in sera of pregnant humans.

Animals↗
PubMed1984

Human gallbladder epithelium: non-specific esterases in cholecystitis.

Esterases active at neutral and acid pH have been demonstrated in human gallbladder epithelium. Reaction to a wide variety of inhibitors and activators suggests that they probably represent the same enzyme with two active sites while a close correlation with acid phosphatase, a known lysosomal enzyme, suggests a lysosomal localization. Esterase activity in the gallbladder mucosa in significantly decreased in chronic cholecystitis. Polyacrylamide gel electrophoresis suggests that cholesterol stones may be associated with a specific type of isoenzyme pattern. Esterase positive cells are present in the inflammatory infiltrate in the lamina propria of the gallbladder in most cases of chronic cholecystitis. Naphthol AS-D chloracetate esterase staining indicates that mast cells form a large part of the infiltrate. Bile acids modulate the enzyme activity in vitro. Although the exact substrate specificity is not known, several possibilities are discussed, implicating esterases in the pathogenesis of chronic cholecystitis.

Acid Phosphatase↗
PubMed2000

Distinct Effect of Benzalkonium Chloride on the Esterase and Aryl Acylamidase Activities of Butyrylcholinesterase.

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) from vertebrates, other than their predominant acylcholine hydrolase (esterase) activity, display a genuine aryl acylamidase activity (AAA) capable of hydrolyzing the synthetic substrate o-nitroacetanilide to o-nitroaniline. This AAA activity is strongly inhibited by classical cholinesterase (ChE) inhibitors. In the present study, benzalkonium chloride (BAC), a cationic detergent widely used as a preservative in pharmaceutical preparations, has been shown to distinctly modulate the esterase and AAA activities of BChEs. The detergent BAC was able to inhibit the esterase activity of human serum and horse serum BChEs and AChEs from electric eel and human erythrocyte. The remarkable property of BAC was its ability to profoundly activate the AAA activity of human serum and horse serum BChEs but not the AAA activity of AChEs. Thus BAC seem to preferentially activate the AAA activity of BChEs alone. Results of the study using the ChE active site-specific inhibitor diisopropyl phosphorofluoridate indicated that BAC binds to the active site of ChEs. Furthermore, studies using a structural homolog of BAC indicated that the alkyl group of BAC is essential not only for its interaction with ChEs but also for its distinct effect on the esterase and AAA activities of BChEs. This is the first report of a compound that inhibits the esterase activity, while simultaneously activating the AAA activity, of BChEs. Copyright 2000 Academic Press.

Journal Article↗
PubMed1997

Acetylcholinesterase and neuropathy target esterase inhibitions in neuroblastoma cells to distinguish organophosphorus compounds causing acute and delayed neurotoxicity.

The differential inhibition of the target esterases acetylcholinesterase (AChE) and neuropathy target esterase (NTE, neurotoxic esterase) by organophosphorus compounds (OPs) is followed by distinct neurological consequences in exposed subjects. The present study demonstrates that neuroblastoma cell lines (human SH-SY5Y and murine NB41A3) can be used to differentiate between neuropathic OPs (i.e., those inhibiting NTE and causing organophosphorus-induced delayed neuropathy) and acutely neurotoxic OPs (i.e., those highly capable of inhibiting AChE). In these experiments, concentration-response data indicated that the capability to inhibit AChE was over 100x greater than the capability to inhibit NTE for acutely toxic, nonneuropathic OPs (e.g., paraoxon and malaoxon) in both cell lines. Inhibition of AChE was greater than inhibition of NTE, without overlap of the concentration-response curves, for OPs which are more likely to cause acute, rather than delayed, neurotoxic effects in vivo (e.g., chlorpyrifos-oxon, dichlorvos, and trichlorfon). In contrast, concentrations inhibiting AChE and NTE overlapped for neuropathy-causing OPs. For example, apparent IC50 values for NTE inhibition were less than 9.6-fold the apparent IC50 values for AChE inhibition when cells were exposed to the neuropathy-inducing OPs diisopropyl phosphorofluoridate, cyclic tolyl saligenin phosphate, phenyl saligenin phosphate, mipafox, dibutyl dichlorovinyl phosphate, and di-octyl-dichlorovinyl phosphate. In all cases, esterase inhibition occurred at lower concentrations than those needed for cytoxicity. These results suggest that either mouse or human neuroblastoma cell lines can be considered useful in vitro models to distinguish esterase-inhibiting OP neurotoxicants.

Animals↗
PubMed1991

Physical mapping of the Esterase-6 locus of Drosophila melanogaster.

The Esterase-6 gene locus of Drosophila melanogaster although well-characterized, has not been definitely mapped by in situ hybridization. In this paper, a high resolution in situ hybridization protocol using an avidin/biotinylated-horseradish peroxidase/diaminobenzidine system was adopted to refine the physical map position of the Esterase-6 locus. Clarity of signal, detail of banding pattern and absence of background allowed the assignment of a 1.8 kb cDNA encoding Esterase-6 to three bands within subsections 69 A1-A3 on the left arm of polytene chromosome 3. These data refine earlier deletion mapping and low resolution in situ hybridization results, which assigned Esterase-6 to 69A1-A5. The potential use of this high resolution in situ hybridization technique in the analysis of the physical organization of the Esterase-6 gene duplication and surrounding region is discussed.

Animals↗
PubMed1994

HPLC separation of enterobactin and linear 2,3-dihydroxybenzoylserine derivatives: a study on mutants of Escherichia coli defective in regulation (fur), esterase (fes) and transport (fepA).

Reversed-phase HPLC separation of enterobactin and its 2,3-dihydroxybenzoylserine derivatives was used for a comparative analysis of mutants of Escherichia coli, defective in the regulation of enterobactin biosynthesis (fur), enterobactin transport (fepA) and enterobactin esterase (fes). A complete separation of all 2,3-dihydroxybenzoylserine compounds was achieved: the monomer (DHBS), the linear dimer (DHBS)2 and trimer (DHBS)3, the cyclic trimer, enterobactin, as well as 2,3-dihydroxybenzoic acid. The production of all these compounds was followed after ethylacetate extraction from acidified culture fluids. Enterobactin was found to be the predominant product in all mutant strains. The mutant strains behaved differently with regard to the breakdown products. All degradation products, such as DHBS, (DHBS)2 and (DHBS)3, were detected in the overproducing fur mutant where both transport and esterase are still functioning, while only the monomer, DHBS, was detected in the fepA mutant and no degradation was found in the esterase-deficient fes mutant. From the pattern of breakdown products it may be inferred that the esterase acts in two different ways, depending on whether transport is functioning or not. Thus, esterolytic cleavage of ferric enterobactin after entering the cells results in a mixture of all three hydrolysis products, i.e. DHBS, (DHBS)2 and (DHBS)3, while cleavage of iron-free enterobactin subsequent to its biosynthesis yields only the monomer. Thus, the results of quantitative HPLC analysis of enterobactin and its breakdown products show that different enterobactin esterase products arise, depending on whether iron is bound to enterobactin or not.

Bacterial Outer Membrane Proteins↗
PubMed1983

Genetics of two tissue esterase polymorphisms (Est-4 and Est-5) in the rabbit.

Two polymorphic esterase systems were found after electrophoresis of rabbit tissue homogenates. Each of these systems is controlled by an autosomal locus with two alleles. Est-4 determines the absence (Est-4a) or presence (Est-4b) of two bands of esterase activity with intermediate anodcal mobility and broad substrate specificity. This polymorphism was found to be present in liver, small intestine, and spleen but not in kidney, heart, and testis. Est-5 is coding for cathodally migrating esterases which differ in mobility (Est-5a and Est-5b). This polymorphism was found only in kidney and testis homogenates. Est-5 esterases are more active against alpha-naphthyl acetate than against beta-naphthyl acetate and have no activity against alpha-naphthyl butyrate. Linkage analysis indicated that Est-4 is localized on rabbit LG VI as part of a cluster of esterase loci, whereas Est-5 segregates independently, Rabbits from two inbred and nine partly inbred strains were tested for these polymorphisms.

Alleles↗
PubMed1986

Activity of esterases in plasma from Ghanaian and British subjects.

We have measured aspirin esterase, cholinesterase, paraoxonase, and phenylacetate esterase activities in samples of plasma from British and Ghanaian subjects. Aspirin esterase, paraoxonase, and phenylacetate esterase activities were significantly lower in Ghanaians compared with British subjects. However, cholinesterase activities were similar in Ghanaian and British plasma samples. The lower esterase activities in Ghanaian plasma samples may result in higher circulating concentrations and greater pharmacological effects of drugs such as aspirin.

Aryldialkylphosphatase↗
PubMed2000

The effect of C1-esterase inhibitor in definite and suspected streptococcal toxic shock syndrome. Report of seven patients.

OBJECTIVE: To evaluate the effect of adjunctive C1-esterase inhibitor substitution therapy on clinical characteristics and outcome of patients with streptococcal toxic shock syndrome (TSS). DESIGN: Observational. SETTING: Medizinische Poliklinik, University of Bonn, Germany. PATIENTS: Seven patients with direct or indirect evidence of streptococcal TSS. INTERVENTION: In addition to conventional and supportive therapy, all patients received 2-3 single doses of C1-esterase inhibitor totaling 6,000-10,000 U within the first 24 h after admission. MEASUREMENTS AND RESULTS: All patients developed fulminant septic shock, multiorgan failure and/or capillary leak syndrome and necrotizing fasciitis within 10-72 h following the onset of first symptoms. Between 1 and 4 days following administration of C1-esterase inhibitor, a marked shift of fluid from extravascular to intravascular compartments took place in all but one patient, accompanied by a transient intra-alveolar lung edema and rapidly decreasing need for adrenergic agents. Six of seven patients survived. CONCLUSIONS: These clinical observations in a small series of patients and the favorable outcome point towards a positive effect of early and high-dose administration of C1-esterase inhibitor as adjunctive therapy in streptococcal TSS. The possible mechanism involved may be the attenuation of capillary leak syndrome (CLS) via early inactivation of complement and contact systems. Controlled studies are needed to establish an improvement of the survival rates of patients with streptococcal TSS following administration of C1-esterase inhibitor.

Adult↗
PubMed2003

Identification of a type-D feruloyl esterase from Neurospora crassa.

Feruloyl esterases constitute an interesting group of enzymes that have the potential for use over a broad range of applications in the agri-food industries. In order to expand the range of available enzymes, we have examined the presence of feruoyl esterase genes present in the genome sequence of the filamentous fungus Neurospora crassa. We have identified an orphan gene (contig 3.544), the translation of which shows sequence identity with known feruloyl esterases. This gene was cloned and the corresponding recombinant protein expressed in Pichia pastoris to confirm that the enzyme (NcFaeD-3.544) exhibits feruloyl esterase activity. Unusually the enzyme was capable of p-coumaric acid release from untreated crude plant cell wall materials. The substrate utilisation preferences of the recombinant enzyme place it in the recently recognised type-D sub-class of feruloyl esterase.

Carboxylic Ester Hydrolases↗
PubMed1992

An affinity-amplified immunoassay for juvenile hormone esterase.

A method is described for increasing the specificity of an immunoassay for catalytically active enzymes and is specifically illustrated with a sensitive assay for an important regulatory enzyme from insects. Trifluoromethyl ketone haptens, potent inhibitors of insect juvenile hormone esterase, were bound to proteins such as hemocyanin (keyhole limpet) and conalbumin (chicken embryo). Haptens containing a thiol group were conjugated using heterobifunctional coupling reagents, and haptens with a carboxylic acid moiety were conjugated by the mixed anhydride method. The trifluoromethyl ketone-protein conjugates, shown to retain their inhibitory activity against juvenile hormone esterase, were used as coating antigens in several solid-phase enzyme-linked immunosorbent assay formats along with specific antibodies raised in rabbits against purified juvenile hormone esterase. The previously unreported format, termed affinity-amplified immunoassay (AAIA), was successfully used for quantitative monitoring of low levels of the esterase in dilute hemolymph and egg homogenates from various lepidopteran insect species, as well as for detection of the native and mutant forms of the enzyme obtained in a recombinant baculovirus expression system. The AAIA format was more sensitive for the target esterase and detected only the catalytically active form of the enzyme.

Animals↗
PubMed1979

Glutathione thiol esterases of human red blood cells. Fractionation by gel electrophoresis and isoelectric focusing.

The number and the substrate specificities of glutathione thiol esterases of human red blood cells have been investigated by gel electrophoresis and isoelectric focusing and staining methods devised for the location of these enzymes on gels. Several glutathione thiol esterase forms, both unspecific (with respect to the S-acyl group of the substrate) and specific were found. Electrophoresis on both polyacrylamide and agarose gels resolved three enzyme components with apparently similar substrate specificity. Isoelectric focusing in liquid column separated two unspecific thiol esterase components with S-lactoylglutathione (pI = 8.4) and S-propionylglutathione (pI = 8.1) as the best substrates, respectively, and two specific enzymes, S-formylglutathione hydrolase (pI = 5.2) and S-succinylglutathione hydrolase (pI = 9.0). Isoelectric focusing on polyacrylamide gel resolved nine unspecific glutathione thiol esterase bands (between pH values 7.0 and 8.4). Partially purified glyoxalase II (S-2-hydroxyacylglutathione hydrolase, EC 3.1.2.6) from erythrocytes or liver still gave three components on electrophoresis and several activity bands on gel electrofocusing. These results indicate that human red cells contain at least four separate glutathione thiol esterases. Glyoxalase II, one of these enzymes, apparently occurs in multiple forms. These were neither influenced by preptreatment of the samples with neuraminidase or thiols nor were interconvertible during the fractionations.

Electrophoresis, Polyacrylamide Gel↗
PubMed1987

Biochemical and genetic evidence for distinct membrane-bound and cytosolic sialic acid O-acetyl-esterases: serine-active-site enzymes.

A cytosolic sialic acid-specific O-acetyl-esterase was previously described that can remove O-acetyl esters from the 9-position of sialic acids. We show that rat liver Golgi vesicles contain a distinct sialic acid-esterase located within the lumen of the same vesicles that add O-acetyl esters to sialic acids. Studies of a retinoblastoma cell line genetically deficient in the cytosolic enzyme also confirm the existence of distinct membrane-associated sialic acid esterase activity. We developed a sensitive, specific and facile assay, which measures release of [3H]acetyl groups from [3H-acetyl]9-O-acetyl-N-acetylneuraminic acid. Using this assay, we show that rat liver membranes may contain different sialic acid O-acetyl-esterases. The membrane-associated enzyme(s) bind to Concanavalin A Sepharose, whereas the cytosolic enzyme does not. Membrane-bound and cytosolic esterases are inactivated by di-isopropyl-fluorophosphate, showing they are serine-active-site enzymes.

Acetylesterase↗
PubMed1990

Observation of tissue prokallikrein activation by some serine proteases, arginine esterases in rat submandibular gland.

Two serine proteases, arginine esterases (esterases I and II) which showed the activity of tissue prokallikrein activation were identified in rat submandibular gland. These enzymes were separated from the homogenate of rat submandibular gland by two successive DEAE-cellulose chromatographies and were further purified and characterized. Esterases I and II were found to be identical with tonin and esterase B-like enzyme, respectively. Both enzymes activated rat urinary prokallikrein at near neutral pH. Esterase B-like enzyme activated rat urinary prokallikrein better than tonin.

Amino Acid Sequence↗
PubMed1982

Evidence for the existence of neurotoxic esterase in neural and lymphatic tissue of the adult hen.

Hen brain and spinal cord contain a number of esterases that hydrolyze phenyl valerate (PV). Most of this activity is sensitive to inhibition by micromolar concentrations of paraoxon. Included among the paraoxon-resistant esterases is neurotoxic esterase (NTE), which is inhibited in vivo and in vitro by certain organophosphorus compounds, such as mipafox, which cause delayed neurotoxicity. Since published information on the NTE content of non-neural tissues was heretofore lacking, a comprehensive study was undertaken of the occurrence of this enzyme in tissues of the adult hen (Gallus gallus domesticus), the species of choice in the study of organophosphorus-induced delayed neurotoxicity. Complete differential titration curves of PV esterase activity were obtained by preincubation of each tissue homogenate with a wide range of concentrations of paraoxon, a non-neurotoxic compound, plus or minus mipafox, a neurotoxic compound, followed by PV esterase assay. Brain NTE activity was determined to be 2426 +/- 104 nmoles.min-1.(g wet weight)-1 (mean +/- S.E.M.). Titration of other tissues resulted in the following NTE activities, expressed as percentages of brain NTE activity: spinal cord (21%), peripheral nerve (1.7%), gastrocnemius muscle (0%), pectoralis muscle (0%), heart (4%), liver (0%), kidney (0%), spleen (70%), spleen lymphocytes (26%), and blood lymphocytes (24%). Using an abbreviated procedure, erythrocytes and plasma showed no NTE activity. These results indicate that NTE has limited distribution among the tissues of the adult hen and is present in lymphatic as well as neural tissue.

Animals↗
PubMed1987

Purification and partial characterization of rat intestinal cefuroxime axetil esterase.

An esterase which hydrolyses the cephalosporin antibiotic, cefuroxime axetil has been isolated from rat intestinal washings and purified. Closely related cefuroxime esters were extremely poor substrates, but p-nitrophenyl acetate and alpha-naphthyl acetate were slowly hydrolysed by the purified enzyme. Analysis by gel filtration gave an Mr = 51,000 and on SDS-polyacrylamide gel electrophoresis the esterase resolved into two main bands of Mr = 31,500 and 26,800. Analytical isoelectric focusing resolved purified esterase into multiple forms active toward alpha-naphthyl acetate, the isoelectric points of which ranged from pH 4.5 to 6.3. The esterase bound specifically to Con A-Sepharose suggesting it could be a glycoprotein. Esterase activity was unaffected by the presence of dihydroxy bile salts (1-8 mM) and inhibition studies using organophosphates and eserine salicylate have classified the enzyme as a carboxylesterase.

Animals↗
PubMed1991

Inhibitor studies of purified haemopoietic (myeloid) cell esterases. Evidence for the existence of distinct enzyme species.

Human myeloid cells synthesize and express two major species of esterase, defined by isoelectric focusing (IEF). The first of these (MonEst) is specifically associated with haemopoietic cells of monocytic lineage, whereas the other species (ComEst) is common to all myeloid cells (granulocytes and monocytes) irrespective of lineage affiliation. Having recently purified these two species of human myeloid cell esterase, this present study extensively investigated the effects of 17 different inhibitors on their ability to hydrolyse the synthetic substrate alpha-naphthyl acetate (alpha NA). Significant inhibition of both ComEst and MonEst was exerted by 1% sodium dodecyl sulphate (SDS) and 1.0 mM diethyl pyrocarbonate (DEPC), but the patterns of inhibition for the two esterase species with the remaining compounds studied differed considerably; for example, 0.2 mM phenylmethylsulphonyl fluoride (PMSF), 5.0 x 10(-3) M dichloroisocoumarin (DCIC) and 0.1 mM N-tosyl-L-phenylalanine chloromethyl ketone (TPCK) all inhibited MonEst but not ComEst. Mechanisms of inhibition were also examined and these studies established that SDS, PMSF, DCIC and TPCK irreversibly inactivated MonEst whilst the inhibition of ComEst by SDS was reversible. Analysis of inhibition kinetics further showed that (a) the reversible inhibition of both ComEst and MonEst by sodium fluoride (NaF) was noncompetitive (with Ki values of 1.28 and 0.01 mM, respectively, indicating a marked difference in sensitivity); (b) the inhibition of MonEst by PMSF was of 'mixed' noncompetitive-competitive type; and (c) that DEPC exerted noncompetitive inhibition with similar Ki values (0.05 mM) for both esterase species. These observations unequivocably demonstrate that ComEst and MonEst are unrelated enzyme species, with a common ability to hydrolyse alpha NA, and that these esterase show marked differences with respect to their active sites as adjudged by inhibitor sensitivities. These observations are particularly relevant to the histochemical analysis of these enzymes and to the elucidation of their in vivo functions.

Acetylesterase↗
PubMed1990

Comparative study of esterases in brains of the vertebrates.

Disc gel electrophoretic patterns of esterases obtained in the buffer (0.1 M Tris-HCl buffer pH 7.4) extracts of the brains of twelve species belonging to various classes of vertebrates ranging from fishes to mammals are compared. Substrate specificity and inhibitor sensitivity is used to classify the enzymes into different classes of esterases. The pattern obtained does not suggest distribution of any specific enzymes to a particular class of vertebrates nor does it suggest any evolutionary change from fish to mammals. Some fast moving bands are observed in fishes and amphibians. Esterases with active thiol groups (Aryl and Esdp esterases) exhibit wide distribution among the species studied. The enzymes which are resistant to inhibition by eserine, pCMB and DFP (Acetyl and ER esterases) are present in the tetrapods studied.

Animals↗