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PubMedDate not supplied

Promotion of peripheral axonopathies by certain esterase inhibitors.

Certain esterase inhibitors were found to exacerbate the clinical signs of polyneuropathy caused by various neurotoxic compounds and to delay the recovery from nerve crush. This phenomenon is referred to as promotion of axonopathies. The molecular target of promotion has not yet been identified. However, all known promoters are also inhibitors of neuropathy target esterase (NTE), the putative target of organophosphate neuropathy, but it has been shown that the target of promotion is unlikely to be NTE. Available data suggest that promoters might affect a target and a mechanism present in the nervous system that is not activated by axonal lesions. Promotion may be important to understand the physiological mechanism of nerve damage and repair. This finding also implies a changing perspective for the risk assessment of exposures to esterase inhibitors, some of which are used as pesticides and might be promoters.

Animals↗
PubMed1981

Antigenic separation of a nonkinin-generating TAMe esterase from human urinary kallikrein and immunohistochemical comparison of their localization in the kidney.

Two urinary enzymes that cleave alpha-N-p-tosyl-L-arginine methyl ester (TAMe) have been separated and utilized to elicit monospecific antisera; only one, urinary kallikrein (urokallikrein), had kinin-generating activity. The nonkinin-generating TAMe esterase and urokallikrein were antigenically unrelated. Immunoperoxidase studies of normal human kidney revealed localization of nonkinin-generating TAMe esterase to epithelial cells of the distal tubule, including the ascending thick limb, the macula densa region, and some areas of convoluted tubule. Immunoreactivity for urokallikrein was confined to reabsorption droplets of proximal tubules and to focal segments of the distal convoluted tubules. Electrophoretic, antigenic, and immunohistochemical studies have established that urokallikrein and a nonkinin-generating TAMe esterase represent two distinct renal distal tubule enzymes.

Antigens↗
PubMed1988

Comparison of the distribution of tissue kallikrein and esterase A, a kallikrein-like enzyme, in rat kidney using specific monoclonal antibodies.

Tissue kallikrein (E.C. 3.4.21.35) and arginine esterase A, another closely related, kinin-generating serine protease, have been localized by immunocytochemistry in rat kidney, using monoclonal antibodies that do not crossreact with other kallikrein-related enzymes or with tonin. Kallikrein was present primarily in the apical cytoplasm of the connecting tubule and the cortical collecting duct. Esterase A, on the other hand, was present primarily in the basolateral region of both proximal and distal straight tubules in the outer medulla and medullary rays. In addition, esterase A was demonstrable in distal convoluted tubules and, to a lesser extent, in proximal convoluted tubules. The presence of different kinin-generating enzymes at these sites would permit the formation of kinins from appropriate substrates on both the vascular and luminal poles of separate segments of the kidney tubule.

Animals↗
PubMed1989

Co-localization of a kallikrein-like serine protease (arginine esterase A) and atrial natriuretic peptide in rat atrium.

Atrial natriuretic peptide (ANP) is stored in atrial granules primarily as a larger molecular weight precursor (pro-ANP), which is believed to be rapidly converted to an active peptide of 28 amino acids during or shortly after secretion. A tissue kallikrein-like serine protease has been suggested as a potential processing enzyme. In the present immunocytochemical study, using specific monoclonal antibodies, we found that esterase A, a kallikrein-like serine protease, was demonstrable in rat atrial myocytes and in ventricular myocytes, and was capable of cleaving pro-ANP to yield a low molecular weight product. Using colloidal gold immunocytochemistry at the electron microscopic level, we have found esterase A in atrial myocytes, both in granules and in another subcellular site that corresponds to sarcoplasmic reticulum. Double-label electron microscopic immunocytochemical results indicated that esterase A can co-localize with ANP in granules of atrial myocytes.

Animals↗
PubMed1989

Histochemical demonstration of neurotoxic esterase.

We developed a histochemical method for localizing neurotoxic esterase (NTE), defined as the phenylvalerate (PV)-hydrolyzing esterase that is resistant to 40 microM paraoxon (A) but inactivated by paraoxon plus 50 microM mipafox (B). NTE is considered to be the target enzyme in the production of organophosphorus ester-induced delayed neurotoxicity (OPIDN). Cryostat sections were incubated in a medium containing alpha-naphthyl valerate and 6-benzamido-4-methoxy-m-toluidine diazonium chloride (fast violet B) after treatment with the above-mentioned inhibitors, leading to formation of an aqueous insoluble precipitate at sites of enzymatic activity. NTE activity was estimated as staining detectable in A but not in B. In the central nervous system (CNS) of chicken, NTE appeared to be present primarily in the somata of most neurons, but at sites indistinguishable from those of the other inhibitor-resistant and -sensitive alpha-naphthyl valerate-hydrolyzing esterases. It could not be distinguished in the CNS of cat, probably because it constitutes less than 3% of the total PV-hydrolyzing activity in the CNS of that species.

Animals↗
PubMed2006

Feruloyl esterase: a key enzyme in biomass degradation.

Feruloyl esterase forms a part of the enzyme complex that acts collectively and synergistically to completely hydrolyze xylan to its monomers. The enzyme has found potential uses in a wide variety of applications of interest to the agrifood and pharmaceutical industries. This review describes the enzymology of feruloyl esterases involved in xylan degradation. The occurrence of feruloyl esterases in various microorganisms and their physiochemical properties are presented. The nature of the enzyme substrates and products, the role of synergistic interactions with xylanases and other accessory enzymes, as well as the sequence-structure relating to the reaction mechanism are emphasized.

Animals↗
PubMed1984

Properties of the arginine esterases from Bitis nasicornis (horned adder) venom.

Five forms of arginine esterase (DE-2 to DE-6) were purified from Bitis nasicornis venom by gel filtration on Sephadex G-50, followed by ion exchange chromatography on CM-cellulose and DEAE-sepharose. They contain 17.6 to 23.1% of carbohydrate, 242 to 244 amino acids including 14 half-cystine residues and have molecular masses of about 38 kDa. The enzymes have a high esterolytic activity towards N alpha-benzoyl-L-arginine ethyl ester but show no proteolytic activity against Azocoll and no clotting activity against fibrinogen. Their sequences of the first 19 amino-terminal residues are the same, but their carbohydrate content shows some variation. Furthermore, sequence studies on the N-terminal regions of the arginine esterases from B. nasicornis venom indicate that they share a significant degree of sequence homology with the kallikrein-like enzymes of Crotalus adamanteus and C. atrox venoms and also with porcine pancreatic kallikrein. Studies on tryptic glycopeptides of the arginine esterases show that carbohydrate occurs at the N-terminal region of the molecule and also towards the center.

Amino Acid Sequence↗
PubMed1985

Comparison of substrates for measuring serum choline esterase activity in hepato-biliary disease.

The efficacy of various substrates for measuring serum choline esterase for the evaluation of hepatic function was studied using o-toluoyl- and succinyl-choline, and acetyl, butyryl- and propionyl-thiocholine. In hepatic disease, the serum choline esterase activity with these substrates was decreased at a similar rate, showing no significant difference. In 78 - 84% of cases with hepatic cirrhosis the enzyme activity with these substrates was less than 50% of the average level of normal individuals, but in acute and chronic hepatitis only 4-9 and 12-14% of patients showed these lower values, respectively. The present study indicates the usefulness of sequential monitoring of serum choline esterase activity with any of these substrates for assessing hepatic disease, particularly cirrhosis, and for monitoring the course of hepatic disease.

Acute Disease↗
PubMed1991

Close linkage of esterase-D to unipolar depression and alcoholism is ruled out in eight pedigrees.

Unipolar depression and alcoholism were tested for genetic linkage to esterase-D at 13q14.1. Tight linkage to esterase-D was ruled out for three phenotypes using three models of penetrance: (1) unipolar depression and alcoholism taken together as affected, (2) unipolar depression alone as affected with alcoholism considered unaffected and (3) alcoholism alone as affected with unipolar depression considered unaffected. This study does not support an earlier finding of possible linkage between the esterase-D locus at 13q14.1 and alcoholism.

Adolescent↗
PubMed1987

Urinary kallikrein and non-kallikrein arginine esterase activities in beagle dogs.

The activity of urinary kallikrein and non-kallikrein arginine esterase was measured in the 16hrs urine of 16 beagle dogs. Enzyme activity was assayed using D-valyl-L-leucyl-L-arginine-p-nitroanilide as a substrate at 30 degrees C, pH 8.0, and the unit of measurement was defined as the activity which catalyzes the hydrolysis of 1 mumol of the substrate per minute. Kallikrein activity ranged from 3.87 to 48.92 (28.48 average) mU/ml of urine, or from 1.05 to 12.51 (4.56 average) U/16 hrs; whereas that of non-kallikrein arginine esterase ranged from 0.06 to 24.28 (7.11 average) mU/ml, or from 0.01 to 9.78 (1.43 average) U/16 hrs. The ratio between the activity of these two enzymes was 1: 0.002-1: 2.98 (1: 0.42 average). Male dogs had a tendency to show a higher enzyme activity than females for urinary kallikrein and non-kallikrein arginine esterase.

Animals↗
PubMed1989

Genetic and cytogenetic analysis of patients showing reduced esterase-D levels and mental retardation from a survey of 500 individuals with retinoblastoma.

The authors have analysed the esterase-D levels in 500 retinoblastoma patients of whom 15 showed red cell enzyme activities of approximately 50% that of normal controls. Chromosome analysis of these 15 patients confirmed the presence of a deletion involving region 13q14 in all cases. Seven of the 15 cases had not previously been diagnosed and all of these showed sub-band deletions within 13q14. None of these seven patients were mentally retarded although the remaining eight who showed larger chromosome deletions demonstrated the full spectrum of psychomotor abnormalities associated with 13q deletions. Two other mentally retarded retinoblastoma patients with normal esterase-D activity showed no karyotypic abnormality, demonstrating that mental retardation cannot be taken to indicate a chromosome deletion in all cases. Eight of the 15 deletion cases were only unilaterally affected. The data presented in this article suggest that esterase-D quantitation could provide the primary means of detection of chromosome deletions in retinoblastoma patients.

Adult↗
PubMed2000

Acquired C1 esterase inhibitor deficiency.

Acquired C1 esterase inhibitor deficiency is a rare condition associated with autoimmune or low-grade lymphoproliferative disorders. Adults or elderly patients are most commonly affected. The diagnosis is suspected when patients present with recurrent angioedema and low serum levels of C4 with normal levels of C3. Low levels of C1q and low C1 esterase inhibitor activity confirm the diagnosis. In this paper, we summarize experience with 22 cases of acquired C1 esterase inhibitor deficiency in the context of a review of the published literature on diagnosis and treatment of this condition.

Adrenal Cortex Hormones↗
PubMed1999

[O,O-dialkyl-S-bromomethylthiophosphates--inhibitors of mammalian choline- and carboxyl esterases: structure-activity relationship].

The interaction kinetics of potential pesticides, O,O-dialkyl S-bromomethylthiophosphates (RO)2P(O) SCH2Br (R = Et, i-Pr, n-Pr, n-Bu, or n-Am) with acetylcholinesterase, butyryl cholinesterase, and carboxyl esterase from warm-blooded animals was studied. All the compounds irreversibly inhibit these esterases, with k1 (M-1 min-1) being 1.8 x 10(4) - 1.9 x 10(6) for acetylcholinesterase, 2.0 x 10(6) - 4.1 x 10(7) for the more sensitive butyryl cholinesterase, and 2.3 x 10(7) - 2.3 x 10(8) and higher for the most sensitive carboxyl esterase. By using the Hansch and Kubinyi technique of multiple regression analysis, we quantitatively analyzed the relationship between the structure and inhibiting activity of these substances toward acetylcholinesterase and butyryl cholinesterase. Hydrophobic interactions were found to be important for the inhibition of both enzymes but are more pronounced in the case of butyryl cholinesterase. On the other hand, steric factors were much more significant in the inhibition of acetylcholinesterase. For both enzymes, the steric hindrances affect the phosphorylation stage of the enzyme.

Animals↗
PubMed2000

Regulation of the juvenile hormone esterase gene by a composite core promoter.

Transcription from the core promoter of the juvenile hormone esterase gene (-61 to +28) requires the presence of both an AT-rich motif (TATA box) and an initiator motif for any transcription to occur, when assayed by either transcription in vitro with lepidopteran Sf9 nuclear extracts or by transient-transfection assay in Sf9 cells. Additional gel-shift experiments indicated that at least one additional binding site is essential for transcription to occur. Mutational analysis in the transcription-in vitro and cell-transfection assays demonstrated that a 14-bp region from +13 to +27 relative to the transcription start site is also essential for transcription to occur. Whereas the wild-type core promoter is highly transcriptionally active, inclusion of additional flanking sequences to position -212 reduces that activity approx. 100-fold, and inclusion of the 5' region out to position -500 reduces transcription by 200-fold. The pattern of dependence on both the AT-rich motif and the initiator for detectable transcription, and the high innate activity being repressed by 5'-binding factors, was recapitulated in mosquito C7-10 cells. This study demonstrates that the cellular juvenile hormone esterase gene is organized as a composite core promoter, dependent on both TATA-box and initiator-binding factors, an organization that has been more commonly reported for viral promoters. This highly active composite core promoter is made more complex by the absolute dependence on the presence of a third site shortly downstream from the initiator, which is distinct from the 'downstream promoter element' described from some TATA-less genes. The juvenile hormone esterase gene thus appears to be a model of a cellular composite core promoter with a multipartite, indispensible requirement for not just both the TATA box and initiator, but also for at least a third core element as well.

Animals↗
PubMed2000

Amplified esterases B1 and A2-B2 in field populations of Culex pipiens from China.

The main organophosphate (OP) resistance mechanism in the Culex pipiens complex is increased activity of esterases A and B. Fourth-stage larvae from 2 field populations of C. pipiens from Gaomi and Kunming, China, were compared for tolerance to parathion, dichlorovos (OP), and bassa (carbamate) insecticides. Both populations were resistant to OPs but not to bassa. Starch gel electrophoresis indicated that elevated esterase activity was correlated with OP resistance. High frequencies of amplified esterase genes B1 and A2-B2 (0.85 and 0.50) were discovered in Gaomi and Kunming, respectively. However, only low levels of gene amplification were detected.

Animals↗
PubMed2002

Effect of genistein, a tyrosine kinase inhibitor, on TAME-esterase induced contractions in rat aorta in vitro.

Effect of genistein, a protein tyrosine kinase inhibitor, on TAME-esterase induced contractions were studied on rat aorta strips in vitro. Data showed that TAME-esterase induced contractions were concentration dependent and these contractions were significantly inhibited when rat aorta strips were pre-incubated with genistein. The present findings provide evidence for the possible contribution of tyrosine kinases during TAME-esterase induced contractions in aorta.

Animals↗
PubMed1992

[Identification of a new penicillinase in a Klebsiella pneumoniae strain of which a mutant also produces an esterase hydrolyzing cephalothin and cefotaxime].

Klebsiella pneumoniae strain L 164 produces a penicillinase whose isoelectric point is 8.1, an unusual figure for this bacterial species. This strain exhibits resistance to conventional penicillins and a synergistic effect is seen with clavulanic acid. In contrast, susceptibility to cephalosporins is marked, as shown by the low minimum inhibitory concentrations (MICs). This phenotype is characteristic of strains with no acquired resistance. A first mutant with MICs for cephalothin and cefotaxime 8-fold to 16-fold those of the initial strain was obtained spontaneously. This mutant's MICs for the other beta-lactams were not substantially changed. In addition to the same penicillinase as the one produced by the parent strain, this mutant produced an acetyl-esterase capable of hydrolyzing the cephalosporins with an acetoxyl side-chain, i.e., cefalothin and cefotaxime, to deacetylated derivates which retain substantial antibacterial activity. Another mutant selected on an amoxicillin gradient produced ten times more penicillinase than the parent strain but no esterase. This second mutant exhibited very high MICs for penicillins and first and second generation cephalosporins. The MIC for cefotaxime was comparable to that seen with the esterase-producing mutant. Among the antimicrobials tested, only third generation cephalosporins and cefoxitin showed adequate activity.

Acetylesterase↗
PubMed2006

[Episodes of angioedema in children with C1 esterase inhibitor deficiency].

A 6-year-old boy and a 3.5-year-old girl presented with unexplained episodes of angioedema without urticaria. Low serum C1 esterase inhibitor activity was found in both children. Family history revealed autosomal dominant inheritance in the girl. The boy had a negative family history for angioedema. C1 esterase inhibitor deficiency is a rare but serious condition that may cause oedema of the upper respiratory tract and death by asphyxiation. Episodes of angioedema occur spontaneously, usually subsiding within 48-72 h. Between episodes, the patients are symptom free. Treatment consists of substitution of synthetic C1 esterase inhibitor during episodes of edema carrying a risk of upper airway obstruction. In patients who have more than one episode of severe angioedema per month, daily treatment with tranexamic acid should be considered. Both of these patients were not receiving daily treatment.

Airway Obstruction↗