Showing papers on "Esterase published in 1985"
TL;DR: It is demonstrated that clones of murine Tc cells possess considerable trypsin-like esterase activity when assayed by a sensitive colorimetric assay and that the ester enzyme activity resides in a protein of relative molecular mass (Mr) 28,000 (28K).
Abstract: Cytotoxic T (Tc) lymphocytes recognize and lyse target cells and are thought to serve as an important defence against viral infections1 and possibly against neoplasms2. The nature of the receptors responsible for antigen recognition by these cells is becoming clearer, but the molecular mechanisms responsible for their cytolytic activity remain largely unknown. The possibility that proteases are involved in this process has been suggested by the effects of certain inhibitors3,4. Here we demonstrate that clones of murine Tc cells possess considerable trypsin-like esterase activity when assayed by a sensitive colorimetric assay. This activity was blocked completely by two serine esterase inhibitors, diisopropylfluorophosphoridate (DFP) and phenylmethylsulphonyl fluoride (PMSF), but not by Nα-tosyl lysyl chloromethyl ketone (TLCK). The use of 3H-DFP as an affinity-labelling reagent demonstrated that the esterase activity resides in a protein of relative molecular mass (Mr) 28,000 (28K). A wide variety of other lymphocytes, including those from thymus, spleen and lymph node, established lines of B cells and noncytotoxic T cells, and clones of T helper cells, had about 300-fold less esterase activity than the Tc-cell clones and far smaller amounts of the DFP-reactive 28K protein. However, in thymocytes the esterase activity increased 20–50-fold and the 28K protein became more prominent 4 days after these cells had been stimulated in vitro to generate Tc cells.
305 citations
TL;DR: The concentration of aspirin relative to salicylate in the circulation may be affected by individual variation in esterase levels and the relative roles of the different esterases, and this may influence the overall pharmacological effect.
Abstract: Esterases, hydrolases which split ester bonds, hydrolyse a number of compounds used as drugs in humans. The enzymes involved are classified broadly as cholinesterases (including acetylcholinesterase), carboxylesterases, and arylesterases, but apart from acetylcholinesterase, their biological function is unknown. The acetylcholinesterase present in nerve endings involved in neurotransmission is inhibited by anticholinesterase drugs, e.g. neostigmine, and by organophosphorous compounds (mainly insecticides). Cholinesterases are primarily involved in drug hydrolysis in the plasma, arylesterases in the plasma and red blood cells, and carboxylesterases in the liver, gut and other tissues. The esterases exhibit specificities for certain substrates and inhibitors but a drug is often hydrolysed by more than one esterase at different sites. Aspirin (acetylsalicylic acid), for example, is hydrolysed to salicylate by carboxylesterases in the liver during the first-pass. Only 60% of an oral dose reaches the systemic circulation where it is hydrolysed by plasma cholinesterases and albumin and red blood cell arylesterases. Thus, the concentration of aspirin relative to salicylate in the circulation may be affected by individual variation in esterase levels and the relative roles of the different esterases, and this may influence the overall pharmacological effect. Other drugs have been less extensively investigated than aspirin and these include heroin (diacetylmorphine), suxamethonium (succinylcholine), clofibrate, carbimazole, procaine and other local anaesthetics. Ester prodrugs are widely used to improve absorption of drugs and in depot preparations. The active drug is released by hydrolysis by tissue carboxylesterases. Individual differences in esterase activity may be genetically determined, as is the case with atypical cholinesterases and the polymorphic distribution of serum paraoxonase and red blood cell esterase D. Disease states may also alter esterase activity.
207 citations
TL;DR: In this article, the structure of the major feruloyl compound was identified as O -(5- O -feruloyls-α- l -arabinofuranosyl)-(1→3)- O -β- d -xylopyranosyl-(1→4)- d -opyranose on the basis of 13 C-n.m.r.
206 citations
TL;DR: Pseudomonas diminuta strain MG hydrolyzes parathion to diethylthiophosphoric acid and p-nitrophenol and the esterase responsible for this reaction is encoded by a gene located on a plasmid termed pCMS1, which resulted in the isolation of transconjugants that exhibitedParathion hydrolase activity.
Abstract: Pseudomonas diminuta strain MG hydrolyzes parathion to diethylthiophosphoric acid and p-nitrophenol. The esterase responsible for this reaction is encoded by a gene located on a plasmid termed pCMS1. The gene was cloned into plasmid pBR322 and the broad host range cloning vector pKT230. Enzyme activity was detected in Escherichia coli strains that contained the recombinant plasmids. A 1.5 kilobase BamHI fragment with single restriction sites for SalI, PstI and XhoI was shown to direct the synthesis of the enzyme. The 1.5 kilobase BamHI fragment was inserted into the high expression vector pUC7, and the resulting recombinant, pCMS40, was used to construct pKT230 derivatives containing the parathion hydrolase gene. Subsequent transfer of the recombinant plasmids into a cured derivative of P. diminuta MG and a p-nitrophenol-utilizing strain of Pseudomonas resulted in the isolation of transconjugants that exhibited parathion hydrolase activity. The highest enzyme activity was observed with P. diminuta MG.
141 citations
TL;DR: The active site specificity of vertebrate collagenase was mapped with the synthesis of a variety of peptides, peptolides, and peptide esters and the enzyme was found to prefer very lipophilic sequences.
Abstract: The active site specificity of vertebrate collagenase was mapped with the synthesis of a variety of peptides, peptolides, and peptide esters. The enzyme was found to prefer very lipophilic sequences, and it was also found to be an esterase. The thio peptolide Ac-Pro-Leu-Gly-SCH[CH2CH(CH3)2]CO-Leu-Gly-OC2H5 was found to be an exceptional substrate. High-performance liquid chromatography and tandem mass spectrometry were used to unambiguously establish the cleavage site in several peptide substrates.
103 citations
TL;DR: The nucleotide sequence of the gene ereA of plasmid pIP1100 which confers high-level resistance to erythromycin (Em) in Escherichia coli is cloned and determined, suggesting that this resistance determinant should be indigenous to E. coli.
99 citations
TL;DR: 3 new spectrophotometric enzyme assays were developed for the study of microbial lignin-degrading enzymes and led to the discovery of an extracellular, aromatic methyl ether demethylase produced by the white-rot fungus Phanerochaete chrysosporium.
Abstract: 3 New spectrophotometric enzyme assays were developed for the study of microbial lignin-degrading enzymes The conversion of 2-methoxy-3-phenylbenzoic acid to 2-hydroxy-3-phenylbenzoic acid led to the discovery of an extracellular, aromatic methyl ether demethylase produced by the white-rot fungus Phanerochaete chrysosporium The conversion of methyl 2-hydroxy-3-phenylbenzoate to 2-hydroxy-3-phenylbenzoic acid allowed the identification of an extracellular, aromatic methyl ester esterase produced by this fungus The Phanerochaete sp also excreted an enzyme complex that oxidized 4-(4-hydroxy-3-methoxyphenyl)-3-buten-2-one, probably to aliphatic products All 3 novel enzyme activities were produced together with, and probably comprise a part of, the Phanerochaete ligninolytic enzyme complex Unlike previously known ligninases, these enzymes did not oxidize 3,4-dimethoxybenzyl alcohol All 3 were H2O2-dependent and were activated by Mn2+ ions
74 citations
TL;DR: Wiedemann et al. as mentioned in this paper used electrophoresis to characterize the esterases in Lucilia cuprina and found that only one of the 16 esterase bands associated with resistance to organophosphorus insecticides.
Abstract: Electrophoresis was used to characterize the esterases in Lucilia cuprina (Wiedemann). Of the 16 esterase bands visualized, only one was associated with resistance to organophosphorus insecticides. In laboratory reference strains, the esterase E3 was consistently found in both susceptible and heterozygously resistant flies, but was absent from homozygously resistant flies. It was postulated that resistant flies possessed a non-staining form of E3, designated E3null. Genetic analyses mapped the locus for E3null to a position in the same region as the gene for organophosphorus resistance. No recombinants between the genes for resistance and E3null were detected. In field populations of L. cuprina from several areas in Australia, a close association was found between the frequency of E (0·97) and the proportion of flies resistant to organophosphorus insecticide (0·967). This association suggests that E3null represents the product of a major resistance gene in terms of the ‘mutant ali-esterase’ theory. E3 as found in susceptible blowflies, represents the ‘original’ ali-esterase, the gene for which mutated to one coding for E3null. This mutant enzyme can hydrolyse organophosphates more efficiently than E3 but has lost the ability to hydrolyse 1- and 2-naphthyl acetate (the substrates used to visualize the esterases after electrophoresis).
73 citations
Journal Article•
TL;DR: Based on the results, it appeared that an arylesterase in human and dog RBC cytosol mediated the hydrolysis of esmolol while an aliphatic esterase mediated the production of esolol in guinea pig and rat plasma.
Abstract: The blood esterase mediating the hydrolysis of esmolol was characterized in several different species including man. In contrast to most ester-containing drugs, hydrolysis of esmolol was mediated by an esterase in the cytosol of red blood cells (RBC) in man and dogs and not in plasma or RBC membrane. Species differences in the esterase activity existed. Guinea pig and rat blood esterase activities were much greater than those in the dog followed by those in man. In addition, the esterase activity in rat and guinea pig blood was localized in plasma and not in RBC. Purified human serum cholinesterase, human RBC membrane acetylcholinesterase, human hemoglobin, human carbonic anhydrases A and B, and human and dog serum albumin were all inactive against esmolol. Esmolol esterase activity in human and dog blood was inhibited by sodium fluoride, EDTA, and p-hydroxymercuribenzoate, but not by echothiophate, eserine, and acetazolamide. In contrast, echothiophate and sodium fluoride, but not eserine, inhibited the esterase activity in rat and guinea pig plasma. Metabolic interaction studies indicated that acetylcholine, succinylcholine, procaine, and chloroprocaine did not interfere with the metabolism of esmolol by human and dog blood. Based on the results, it appeared that an arylesterase in human and dog RBC cytosol mediated the hydrolysis of esmolol while an aliphatic esterase mediated the hydrolysis of esmolol in guinea pig and rat plasma.
73 citations
TL;DR: An esterase activity has been found, both in the cell-free growth medium and on the cell surface of the hydrocarbon-degrading Acinetobacter calcoaceticus RAG-1, which catalyzed the hydrolysis of acetyl and other acyl groups from triglycerides and aryl and alkyl esters.
Abstract: An esterase activity has been found, both in the cell-free growth medium and on the cell surface of the hydrocarbon-degrading Acinetobacter calcoaceticus RAG-1. The enzyme catalyzed the hydrolysis of acetyl and other acyl groups from triglycerides and aryl and alkyl esters. Emulsan, the extracellular heteropolysaccharide bioemulsifier produced by strain RAG-1, was also a substrate for the enzyme. Gel filtration showed that the cell-free enzyme was released from the cell surface either emulsan free or associated with the bioemulsifier. The partially purified enzyme was found to interact specifically with the esterified fully active emulsan, but not with the deesterified polymer. A role for esterase in emulsan release from the cell surface was indicated when the enzyme was preferentially depleted from the cell surface under conditions in which emulsan was not released. Such cells lost the capacity to release the biopolymer.
71 citations
TL;DR: Embryogenic callus and suspension cultures secreted a musilagenous polysaccharide whose production was stimulated by 2,4-dichlorophenoxyacetic acid and may be related to the ‘cementing layer’ in maize kernels.
TL;DR: The results are interpreted as indicating that the control point or rate-limiting step in the metabolism of the estradiol esters is the esterase that hydrolyzes the esters toEstradiol, and the prolonged estrogenic action of the C-17-alkyl ester is due to the slow release of estradio from this hydrophobic reservoir.
Abstract: The C-17 fatty acid esters of estradiol are naturally occurring estrogens which have been shown to circulate in blood. They are long-acting estrogens, analogous to the synthetic alkyl and aryl esters of estrogens which have been used pharmacologically for decades. To determine the mechanisms involved in the prolonged stimulation evoked by these nonpolar estrogens, several C-17 alkyl esters were synthesized and labeled with 3H at C-17 alpha, and their metabolism and clearance were studied and compared to those of estradiol in rats. The conversion of the C-17-3H to 3H2O was used as a marker of metabolism. While the clearance of the long chain esters from blood is somewhat slower than that of estradiol (t 1/2 = approximately 16 vs. 2 min, respectively), the rates of metabolism are dramatically different. For example, the t 1/2 of metabolism for two representative esters, estradiol-17-stearate and arachidonate, are 580 and 365 min, respectively, while the t 1/2 of metabolism for estradiol is about as fast as its clearance from blood (approximately 2 min). When the effect of chain length was studied, it was found that for the smaller esters, there was an inverse relationship between the size of the acyl group and the clearance from blood, i.e. the longer carboxylic acids were cleared more slowly. However, when the acyl group was lengthened from C12 to C14, the rate of clearance increased and was even faster with C18. Nevertheless, with all of the esters tested, the rate of metabolism steadily decreased as the chain length increased. These results are interpreted as indicating that the control point or rate-limiting step in the metabolism of the estradiol esters is the esterase that hydrolyzes the ester to estradiol. Thus, the prolonged estrogenic action of the C-17-alkyl esters is due to the slow release of estradiol from this hydrophobic reservoir.
TL;DR: A simple method for the effective, covalent, immobilization of porcine liver esterase ( PLE) is described and the application of this reagent for the preparation of chiral building blocks on a 50 – 500 mmol scale is demonstrated.
TL;DR: In this article, the bicyclic and rather rigid meso-diesters 1 - 3 have been found to be good substrates for pig liver esterase, and the half-esters obtained have been converted to either one of the enantiomers of tricyclic lactones, of potential value for natural product synthesis.
TL;DR: A two‐dimensional electrophoretic profile (2‐DEP) is proposed which considerably refined the degree of esterase polymorphism and improved the enzymic differentiation between and within bacterial species.
Abstract: Esterases produced by different bacterial species were separated by conventional electrophoresis (CE) in polyacrylamide agarose gel and by thin-layer isoelectric focusing (IEF). Although CE revealed the greatest number of esterases and was preferable for their identification by specific hydrolytic activities, the two techniques appeared to be complementary in their resolving power for detection of electrophoretic variants. Consequently, by establishing a direct correspondence between homologous esterase bands resolved by CE and IEF, we have proposed a two-dimensional electrophoretic profile (2-DEP) which considerably refined the degree of esterase polymorphism and improved the enzymic differentiation between and within bacterial species.
TL;DR: Immunoprecipitation and inhibition experiments confirm that this microsomal lipase differs from the palmitoyl-CoA hydrolases of rat liver cytosol and mitochondria, and it is concluded that the two esterase preparations are identical.
Abstract: Two purified carboxylesterases that were isolated from a rat liver microsomal fraction in a Norwegian and a German laboratory were compared. The Norwegian enzyme preparation was classified as palmitoyl-CoA hydrolase (EC 3.1.2.2) in many earlier papers, whereas the German preparation was termed monoacylglycerol lipase (EC 3.1.1.23) or esterase pI 6.2/6.4 (non-specific carboxylesterase, EC 3.1.1.1). Antisera against the two purified enzyme preparations were cross-reactive. The two proteins co-migrate in sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. Both enzymes exhibit identical inhibition characteristics with Mg2+, Ca2+ and bis-(4-nitrophenyl) phosphate if assayed with the two substrates palmitoyl-CoA and phenyl butyrate. It is concluded that the two esterase preparations are identical. However, immunoprecipitation and inhibition experiments confirm that this microsomal lipase differs from the palmitoyl-CoA hydrolases of rat liver cytosol and mitochondria.
TL;DR: Malathion resistance in Anopheles arabiensis from Sudan is monofactorially inherited and is expressed in the adults but not in the larvae, and the resistance is suppressed by the esterase synergist, triphenylphosphate.
TL;DR: Pig liver esterase and α-chymotrypsin catalysed hydrolysis of the meso-diesters 1, 2 and 3 gave the corresponding monoesters which then could be transformed into enantiomerically pure (S )-α-methyphenylanine and (S) -α-methyl-3,4-dihydroxyphenylalanine as discussed by the authors.
TL;DR: Findings suggest that esters whose chain length exceeds 4 carbons will be hydrolyzed primarily by BuE, and the dominance of BuChE in ocular tissues is another factor which merits consideration in the design and evaluation of ocular ester prodrugs.
Abstract: A methodology was developed to determine the proportion of acetyl-(AChE) and butyrylcholinesterase (BuChE) in the albino and pigmented rabbit eye. It was found that BuChE contributed over 75% of the cholinesterase activity in all the ocular tissues but the corneal epithelium of the albino rabbit. This esterase was principally responsible for the parabolic chain length dependence of ocular hydrolysis of model naphthyl ester prodrugs reported previously. In contrast, when incubated with AChE, the rate of hydrolysis of these esters decreased monotonically with increasing ester chain length. Together these findings suggest that esters whose chain length exceeds 4 carbons will be hydrolyzed primarily by BuChE. It is suggested that the dominance of BuChE in ocular tissues is another factor which merits consideration in the design and evaluation of ocular ester prodrugs.
TL;DR: Plasma pseudocholinesterase and porcine liver esterase were used to catalyse the incorporation of the stable isotope oxygen-18 into the carboxyl moiety of lipoxygenase metabolites of arachidonic acid.
Abstract: Plasma pseudocholinesterase and porcine liver esterase were used to catalyse the incorporation of the stable isotope oxygen-18 into the carboxyl moiety of lipoxygenase metabolites of arachidonic acid. This simple method produces eicosanoid products containing two oxygen-18 atoms; but the enzymes studied were found to display large substrate specificity in the efficiencies at which oxygen-18 could be incorporated into the lipoxygenase metabolites. Furthermore, [18O2]LTB4 was found not to back exchange during in vitro incubation with human neutrophils. The methods involved for stable isotope incorporation are simple, efficient and produce highly enriched species in a short time. By varying the type of esterase, the amount of esterase or the length of incubation highly enriched species of all eicosanoids tested could be prepared.
TL;DR: The JH ester-hydrolyzing activity in the larval hemolymph of the tobacco hornworm was found to be attributed to two forms of esterase with almost equivalent activity based on selectivity and kinetics of inhibition by two 3-substituted thio-1, 1,1,1-trifluoropropan-2-ones and a phosphoramidothioate.
TL;DR: Different substrate specificities and a different Km toward acetylthiocholine, as well as different rates of malathion and paraoxon hydrolysis between the Hirokawa and CSMA strains, suggest a qualitative difference in the pI 5.1 esterase from the E1 strain which has a different substrate specificity when compared to the esterases from the other strains.
TL;DR: A qualitative screening revealed the occurrence of lipase, esterase, protease, amylase, endo-1,4-β-D-glucanase, xylanase, pectinmethylesterase and polygalacturonase activities in the technical Aspergillus niger enzyme under study.
Abstract: A qualitative screening revealed the occurrence of lipase, esterase, protease, amylase, endo-1,4-β-D-glucanase, xylanase, pectinmethylesterase, polygalacturonase, catalase, β-D-glucosidase and β-D-galactosidase activities in the technical Aspergillus niger enzyme under study (Lipase 2212 D, Rohm). The isolation and purification of lipolytic activities were performed by combination of DEAE-Trisacryl M ion exchange chromatography, Sephadex G 50 gel filtration and hydrophobic chromatography using Phenylsepharose CL-4B. The individual purification steps were checked by specific enzyme visualization in ultrathin agar gels after ultrathin-layer isoelectric focusing (UIEF). Two UIEF homogeneous lipase isoenzymes (I and II) were isolated and characterized by the following parameters: isoelectric points (I: 4.0; II. 3.5); molecular weights (I: 31000 daltons; II: 19000 daltons); carbohydrate contents (I: 6%; II: 9%) and compositions; pH optima (I, II: 5-6); substrate specificities and various effectors.
TL;DR: The glycoprotein egasyn complexes with and stabilizes precursor beta-glucuronidase in microsomes of several mouse organs and is, in addition, an esterase.
TL;DR: Six to seven esterases from mouse, rat, and rabbit liver microsomes were resolved by chromatofocusing in the pH range 7–4, and each esterase peak showed a different substrate specificity pattern with the substrates evaluated.
TL;DR: It is predicted that pure P(+) isomers may cause delayed neuropathy in hens dosed at about unprotected LD50: prophylaxis and therapy against acute cholinergic effects would have to raise LD50 1000-fold before birds could tolerate potentially neuropathic doses of P(-) isomers.
TL;DR: One of the previously described five purified monoglyceride-cleaving carboxylesterases from rat liver microsomes proved to be a carnitine ester hydrolase, which is most active with medium-chain acyl-L-carnitines and remarkably active with 1,3-diglycerides.
TL;DR: The data in their entirety are interpreted to show that the p-nitrophenylphosphatase activity is a unique property of carbonic anhydrase III and that excessive amounts of the arginine-modifying reagent lead to unspecific structural changes of the enzyme as a result of which all of its enzymatic activities are inactivated.
Abstract: Mammalian carbonic anhydrase III has previously been shown to catalyze the hydrolysis of p-nitrophenyl phosphate in addition to possessing the conventional CO2 hydratase and p-nitrophenylacetate esterase activities. Modification of pig muscle carbonic anhydrase III with the arginine reagent phenylglyoxal yielded two clearly distinctive results. Reaction of the enzyme with phenylglyoxal at concentrations equivalent to those of the enzyme yielded stoichiometric inactivation titration of the enzyme's phosphatase activity, approaching 100% loss of activity with the simultaneous modification of one arginine residue, the latter based on a 1:1 reaction of phenylglyoxal with arginine. At this low ratio of phenylglyoxal to enzyme, neither the CO2 hydratase activity nor the acetate esterase activity was affected. When the modification was performed with a significant excess of phenylglyoxal, CO2 hydratase and acetate esterase activities were diminished as well. That loss of activity was accompanied by the incorporation of an additional half dozen phenylglyoxals and, presumably, the modification of an equal number of arginine residues. The data in their entirety are interpreted to show that the p-nitrophenylphosphatase activity is a unique property of carbonic anhydrase III and that excessive amounts of the arginine-modifying reagent lead to unspecific structural changes of the enzyme as a result of which all of its enzymatic activities are inactivated.
TL;DR: Preparative-scale pig liver esterase-catalyzed hydrolyses of five-membered ring meso-1,3-diesters are enantiotopically selective.
Abstract: Preparative-scale pig liver esterase-catalyzed hydrolyses of five-membered ring meso-1,3-diesters are enantiotopically selective. While pro-S enantiotopic selectivity is exhibited in each case, the...
TL;DR: The influence of allelochemicals and host plants on two hydrolases, α -naphthyl acetate ( α -NA) esterase and styrene oxide hydrolase, was investigated in the fall armyworm, Spodoptera frugiperda.
Abstract: The influence of allelochemicals and host plants on two hydrolases, α -naphthyl acetate ( α -NA) esterase and styrene oxide hydrolase, was investigated in the fall armyworm, Spodoptera frugiperda (J. E. Smith). The α -NA esterase was induced by a range of allelochemicals. Celery, potato, and parsley were also active in inducing the esterase, whereas a number of other host plants had no significant effect. Styrene oxide hydrolase was moderately induced by indole 3-carbinol, peppermint oil, and phenobarbital, but none of the host plants showed any inductive effect.