The Experts below are selected from a list of 195 Experts worldwide ranked by ideXlab platform
Douglas D Anspaugh - One of the best experts on this subject based on the ideXlab platform.
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assays for the classification of two types of Esterases carboxylic ester hydrolases and phosphoric triester hydrolases
Current protocols in immunology, 2002Co-Authors: Douglas D AnspaughAbstract:Assays for the Classification of Two Types of Esterases: Carboxylic Ester Hydrolase and Phosphoric Triester Hydrolase (Douglas D. Anspaugh and Michael Roe, North Carolina State University, Raleigh, North Carolina). This unit describes assays that quantitate two types of esterase the carboxylic ester hydrolases and the phosphoric triester hydrolases. Carboxylic ester hydrolases include the B-Esterases, which are inhibited by organophosphorus compounds. Among the phosphoric triester hydrolases is aryldialkylphosphatase, which has been called A-esterase or paraoxonase due to its ability to oxidize paraoxon and other organophosphates. These assays are colorimetric and miniaturized for rapid simultaneous testing of multiple, small-volume samples in a microtiter plate format. There is also a discussion of the history of esterase nomenclature and the reasons why this large group of enzymes is so difficult to classify.
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Current Protocols in Toxicology - Assays for the Classification of Two Types of Esterases: Carboxylic Ester Hydrolases and Phosphoric Triester Hydrolases
Current protocols in immunology, 2002Co-Authors: Douglas D AnspaughAbstract:Assays for the Classification of Two Types of Esterases: Carboxylic Ester Hydrolase and Phosphoric Triester Hydrolase (Douglas D. Anspaugh and Michael Roe, North Carolina State University, Raleigh, North Carolina). This unit describes assays that quantitate two types of esterase the carboxylic ester hydrolases and the phosphoric triester hydrolases. Carboxylic ester hydrolases include the B-Esterases, which are inhibited by organophosphorus compounds. Among the phosphoric triester hydrolases is aryldialkylphosphatase, which has been called A-esterase or paraoxonase due to its ability to oxidize paraoxon and other organophosphates. These assays are colorimetric and miniaturized for rapid simultaneous testing of multiple, small-volume samples in a microtiter plate format. There is also a discussion of the history of esterase nomenclature and the reasons why this large group of enzymes is so difficult to classify.
H. A. Rose - One of the best experts on this subject based on the ideXlab platform.
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The Use of Polyacrylamide Gel Electrophoresis for the Investigation and Detection of Fenitrothion and Chlorpyrifos-Methyl Resistance in Oryzaephilus surinamensis (Coleoptera: Silvanidae)
Pesticide Biochemistry and Physiology, 2020Co-Authors: Louise C. Rossiter, Robin V. Gunning, H. A. RoseAbstract:Esterase activity in 16 strains of Oryzaephilus surinamensis (L.) with different degrees of resistance to chlorpyrifos-methyl and fenitrothion were investigated quantitatively and qualitatively. Chlorpyrifos-methyl resistance strongly and positively correlated with total esterase activity, whereas there was a moderate relationship between fenitrothion resistance and esterase activity. Polyacrylamide gel electrophoresis (PAGE) provided visual confirmation of these relationships and identified qualitative differences in esterase activity between the two highly chlorpyrifos-methyl strains. Both methods revealed that the elevated esterase activity was not acetylcholinesterase based. The involvement of elevated esterase activity in resistance was confirmed through its inhibition by chlorpyrifos and chlorpyrifos oxon. PAGE was identified as an effective tool for the simple and rapid detection of resistance due to the activity of Esterases and is more powerful than quantitative total esterase assays due to its ability to identify both quantitative and qualitative differences.
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Two Qualitatively Different B-Esterases from Two Organophosphate-Resistant Strains of Oryzaephilus surinamensis (Coleoptera: Silvanidae) and Their Roles in Fenitrothion and Chlorpyrifos-Methyl Resistance
Pesticide Biochemistry and Physiology, 2001Co-Authors: Louise C. Rossiter, Christine M. Conyers, Alan D. Macnicoll, H. A. RoseAbstract:The esterase properties of two highly chlorpyrifos-methyl-resistant strains of Oryzaephilus surinamensis differentially resistant to fenitrothion were investigated. Isoelectric focusing of whole insect homogenates revealed qualitative differences in the isozymes present, with differences in both the number of Esterases with elevated activity in each strain and the ionic charge of these isozymes between strains. These Esterases were concluded to be B-Esterases, with no evidence of A-esterase activity in whole insect homogenates. Native polyacrylamide gel electrophoresis and isoelectric focusing also revealed qualitative differences between strains in the esterase with the greatest activity, purified using ion-exchange chromatography. These differences were thought to be configurational, with SDS-PAGE revealing no difference in the electrophoretic mobility of the two esterase bands, each having a molecular weight of 71 kDa. There was also no difference found in the sequence of the first 15 N-terminal amino acids. Inhibition assays of the purified enzyme samples using the specific insecticidal inhibitors of chlorpyrifos oxon and fenitrooxon revealed that the Esterases from these strains were highly sensitive to inhibition by chlorpyrifos-methyl oxon and significantly less sensitive to inhibition by fenitrooxon. The enzyme sample from insects of MH130f was found to be 247 times less sensitive to fenitrooxon than chlorpyrifos-methyl oxon inhibition. The esterase sample from insects of strain HH012f, highly resistant to both insecticides, was 21 times more sensitive to fenitrooxon inhibition than the sample from MH130f, with intermediate fenitrothion resistance. Differences in the qualitative esterase properties of these strains were proposed as an explanation of the differences in fenitrothion sensitivity and resistance.
Fengqin He - One of the best experts on this subject based on the ideXlab platform.
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elevated Esterases exhibiting arylesterase like characteristics in an organophosphate resistant clone of the greenbug schizaphis graminum homoptera aphididae
Pesticide Biochemistry and Physiology, 2000Co-Authors: Fengqin HeAbstract:Abstract The profiles of esterase activity in an organophosphate (OP)-susceptible (OSS) clone and an OP-resistant (OR-2) clone of the greenbug ( Schizaphis graminum ) were compared using nondenaturing polyacrylamide gel electrophoresis (PAGE) coupled with esterase assays after gel fractionations. A distinct peak of esterase activity was found in the esterase profiles of the OR-2 clone but not in the OSS clone. The peak represents the elevated Esterases identified previously and constitutes a major biochemical difference between the OSS and the OR-2 clones. The Esterases within that peak hydrolyzed five substrates, including phenyl acetate (PA), β-naphthyl acetate (β-NA), α-naphthyl butyrate (α-NB), p -nitrophenyl acetate ( p -NA), and α-naphthyl acetate (α-NA). The most preferred substrate was PA followed by β-NA, α-NB, p -NA, and α-NA. Nondenaturing PAGE revealed that the major esterase peak was contributed by three different esterase bands. These Esterases showed a similar affinity to β-NA and were highly sensitive to inhibition by both paraoxon and p -hydroxymecuribenzoic acid. In addition, the enzyme activity was slightly to moderately activated by Ca 2+ , but significantly inhibited by Triton X-100. These characteristics suggested that the elevated Esterases in the OR-2 clone were arylEsterases or arylesterase-like Esterases with certain biochemical properties resembling phosphoric triester hydrolase. However, these arylesterase-like Esterases were not able to efficiently utilize paraoxon and chlorpyrifos-oxon as their substrates. Thus, the elevated Esterases identified in the OR-2 clone appeared to contribute to OP resistance by sequestrating OP molecules.
Lene Lange - One of the best experts on this subject based on the ideXlab platform.
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a new functional classification of glucuronoyl Esterases by peptide pattern recognition
Frontiers in Microbiology, 2017Co-Authors: Jane Wittrup Agger, Peter Kamp Busk, Bo Pilgaard, Anne S Meyer, Lene LangeAbstract:Glucuronoyl Esterases are a novel type of enzymes believed to catalyse the hydrolysis of ester linkages between lignin and glucuronoxylan in lignocellulosic biomass, linkages known as lignin carbohydrate complexes. These complexes contribute to the recalcitrance of lignocellulose. Glucuronoyl Esterases are a part of the microbial machinery for lignocellulose degradation and coupling their role to the occurrence of lignin carbohydrate complexes in biomass is a desired research goal. Glucuronoyl Esterases have been assigned to CAZymes family 15 of carbohydrate Esterases, but only few examples of characterized enzymes exist and the exact activity is still uncertain. Here peptide pattern recognition is used as a bioinformatic tool to identify and group new CE15 proteins that are likely to have glucuronoyl esterase activity. 1024 CE15-like sequences were drawn from Genbank and grouped into 24 groups. Phylogenetic analysis of these groups made it possible to pinpoint groups of putative fungal and bacterial glucuronoyl Esterases and their sequence variation. Moreover, a number of groups included previously undescribed CE15-like sequences that are distinct from the glucoronoyl Esterases and may possibly have different esterase activity. Hence, the CE15 family is likely to comprise other enzyme functions than glucuronoyl esterase alone. Gene annotation in a variety of fungal and bacterial microorganisms showed that coprophilic fungi are rich and diverse sources of CE15 proteins. Combined with the lifestyle and habitat of coprophilic fungi, they are predicted to be excellent candidates for finding new glucuronoyl esterase genes.
Blair D Siegfried - One of the best experts on this subject based on the ideXlab platform.
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amplification and methylation of an esterase gene associated with insecticide resistance in greenbugs schizaphis graminum rondani homoptera aphididae
Insect Biochemistry and Molecular Biology, 1999Co-Authors: Jeffrey J Swanson, Linda M Field, A L Devonshire, Blair D SiegfriedAbstract:Abstract The greenbug aphid, Schizaphis graminum (Rondani) has developed resistance to organophosphorus insecticides by the over-production of Esterases that have been classified as Type I and Type II. The first twenty N-terminal amino acids of the Type I esterase were determined and used to design an oligonucleotide, which in conjunction with an active site primer derived from conserved sequences of other insect Esterases and two internal primers specific for Esterases from another aphid species resulted in a 0.85 kb genomic DNA fragment from resistant greenbugs. This was extended by 5′ RACE which provided approximately 1.2 kb of the 5′ end of the esterase gene. The 5′ DNA sequence corresponded to 19 of the 20 known amino acids of the Type I esterase, with the last needing only a one base change (probably resulting from a PCR artifact). Furthermore, the sequence showed very close similarity to the amplified E4/FE4 esterase genes of Myzus persicae (Sulzer). A comparison of sequences suggested that the S. graminum gene has introns in the same positions as the first two introns of E4/FE4, with the second intron being considerably larger in S. graminum. Probing of Southern blots with the 0.85 kb esterase fragment showed that the gene encoding the Type I esterase is amplified 4- to 8-fold in resistant S. graminum and that the amplified sequences contain 5-methylcytosine at MspI/HpaII sites, again in agreement with previous findings for M. persicae genes.