• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.4
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• pp.367-371
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• 2005

About 3,000 bacterial colonies with esterase activities were isolated from soil samples by enrichment culture and halo-size on Luria broth-tributyrin (LT) plates. The colonies were assayed for esterase activity in microtiter plates using enantiomerically pure (R)- and (S)-2-phenylbutyric acid resorufin ester (2PB-O-res) as substrates. Two enantioselective strains (JH2 and JH13) were selected by the ratio of initial rate of hydrolysis of enantiomerically pure (R)- and (S)-2-PB-O-res. When cell pellets were used, both strains showed high apparent enantioselectivity ($E_{app}>100$) for (R)-2PB-O-res and were identified as Exiguobacterium acetylicum. The JH13 strain showed high esterase activity on p-nitrophenyl acetate (pNPA), but showed low lipase activity on p-nitrophenyl palmitate (pNPP). The esterase was located in the soluble fraction of the cell extract. The crude intracellular enzyme preparation was stable at a pH range from 6.0 to 11.0.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.243-246
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• 2005

A novel esterase showing high enantioselectivity to (S)-ketoprofen ethyl ester was selected from fosmid environmental DNA library which is provided by Microbial Genomic & Applications Center. As a result of Blast search, the gene wasn't registerated in Gene Bank yet. And as we know, conserved domain region of esterase , G-X-S-X-G, wasn't discovered.$^{4)}$ And it is similar to Beta-lactamase. The DNA sequence of cloned esterase include an open reading frame consisting of 1170 bp, designated as EST-Y29, encoding a protein of 389 amino acids with a molecular mass of about 42.8 kDa. And amino acid sequence analysis revealed only a few identity (28%) to tile known esterases/lipases in the databases containing the conserved sequence motifs of esterases/lipases. when being comparison to other esterase revealed , this enzyme seems to be classified as a new member of esterase family. EST-Y29 was functionally overexpressed in a soluble form in E. coli with maximum conversion yield of (S)-ketoprofen at $65^{\circ}C$. This study demonstrates that functional screening combined with the sequential uses of restriction enzymes to exclude already known enzymes is a useful approach for isolating novel enzyme from a metagenome.

• Korean journal of applied entomology
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• v.35 no.1
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• pp.74-79
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• 1996

General esterases were analysed quantitatively and qualitatively to see their role in deltamethrin resistance mechanisms of the diamondback moth, Plutella xylostella L. Selection with 0.1 g of deltamethrin in each generation induced the moth to decrease susceptibility to the insecticide and to increase esterase activities of the fourth instar larvae. Both characters were highly correlated so that the correlation coefficient (r) between LDSo @g) of deltamethrin and esterase activities (~M/min/pg) was 0.9918 (P=0.0082). Nondenaturing PAGE (6%) separated 17 esterase bands from the whole body extracts of the fourth instar larvae. Deltamethrin-selected populations had fewer esterase bands than had the unselected. Four esterase bands (E3, E4, Ell, and E13) were, however, specific to deltamethrin-selected populations.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.3
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• pp.179-182
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• 2001

Porcine liver esterase was immobilized in polyacrylamide gel for the enantioselective production of levofloxacin from ofloxacin butyl ester. The initial activity of immobilized esterase was found to be significantly affected by the polyacrylamide gel composition. The optimum concentrations of monomer and crosslinker were determined to be 20% and 8.3%, respectively. The activity of immobilized esterase was 55.4% compared to a free enzyme. Enantiomeric excess was maintained at 60%, almost the same level as that of free enzyme. In addition, the immobilized esterase could be used repeatedly up to 10 times without experiencing any severe loss of activity and enantioselectivity.

• Korean journal of applied entomology
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• v.37 no.2
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• pp.179-185
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• 1998

The effect of physiological factors of beet armyworm, Spodoptera exigua (Hubner), on esterase variation was analyzed by comparing electrophoretic esterase isozymes. Each esterase isozyme was also characterized by substrate and inhibitor specificities. A total of 28 esterase isozymes were separated on 10% nondenaturing polycarylamide gel electrophoresis (PAGE). These isozymes were denoted from El to E28 according to cathodal migration distances. There was a variation in esterase isozymes among developmental stages. Larvae and pupae had more isozymes than did adults. Eggs had only eight isozymes. The isozymes of El and E2 were specific only in the first instar larvae. Esterases also showed variation according to different tissues. More kinds of esterase isozymes were found in epidermis and gut tissues than in hemolymph and fat body. Some isozymes were specific in epidermis (from El to E6), gut (E10, El 1, E25, E26, and E27), and hemolymph (E18). Among 10 naphthyl esters, a-naphthyl propionate was the most reactive substrate to the esterase isozymes. The isozymes were classified into cholinesterases (El0 and E24), arylesterases (E4, E9, E17, E19, E21, and E23), and carboxylesterases (the others) on the basis of inhibition by the esterase inhibitors-eserine, dichlorovos, moncrotophos, and paraoxon.

• Korean journal of applied entomology
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• v.33 no.2
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• pp.74-80
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• 1994

The german cockroach, Blattello germanica L, populations were successively selected with dlchlowos for 11 generations. The resulting selected shin was investigated the resistance development. the cross resistance and the esterase actim@. In the dichlowos-selected(Rd) strain, the values of LCs increased 858 times more compared to the susceptible (S) strain. In the dich!o~vos-selected (Rd) strains, the cross-res~stance to chlorpyrifos, propoxur, fenvalerate and pemethnn showed 3.35. 4.09. 283 and 2.00 times. Esterase.activity of the Rd strain showed 1.33 times higher than that of the S strain in the filter paper test. In comparison of zymogram paitems of the estemse isoryme by thin agarose gel electrophoresis against the german cockroach, the S strain was separated by 4 bands uf esterase 3, 5, 6 and 8 bands and the Rd strain was separated by 6 bands of esterase 1, 2, 4, 5, 7 and 8 bands, and the resistant mechanisms of the Rd strain were considered as the 4 bands of esterase-1.2.4 and 7 bands except the common 2 bands of esterase.6 and 8 bands.

• Journal of Microbiology and Biotechnology
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• v.16 no.1
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• pp.145-148
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• 2006

A new functional lipolytic enzyme (AT4) has recently been found from Agrobacterium tumefaciens C58 Cereon using a genome-wide approach. The enzyme has some sequence similarity to E. coli acetyl hydrolase, Emericella nidulans lipase, Moraxella sp. lipase, Acinetobacter lwoffii esterase, and Streptomyces hygroscopicus acetyl hydrolase. However, the sequence similarities are very low (less than $25\%$), suggesting that it is a new lipase/esterase enzyme. ill the present study, intact cell of the A. tumefaciens strain was shown to have lipolytic activity on a tributyrin-LB plate. The AT4 gene was then expressed at a high level in E. coli BL21 (DE3) cells and the enzyme was purified simply by Ni-NTA column chromatography. The purified enzyme showed hydrolytic activity toward p-nitrophenyl caproate, but not toward olive oil, suggesting that the AT4 enzyme was a typical esterase rather than lipase. AT4 esterase had a maximum hydrolytic activity at $45^{\circ}C$ and pH 8.0, when p-nitrophenyl caproate was used as a substrate. It was relatively stable up to $40^{\circ}C$ and at pH 5.0-9.0. Calcium ion and EDT A did not affect the activity and thermal stability of the enzyme. As for substrate specificity, AT4 enzyme could rapidly hydrolyze acetyl and butyl groups from p-nitrophenyl esters and 1-naphthyl esters. In addition, it also released acetyl residues from acetylated glucose and xylose substrates. Therefore, this new esterase enzyme might be used as a biocatalyst in acetylation and deacetylation reactions performed in the fine chemical industry.

• Korean Journal of Microbiology
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• v.39 no.2
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• pp.83-88
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• 2003

We cloned a gene encoding acetyl xylan esterase(axeA) of Streptomyces coelicolor A3(2) and studied its expression pattern in Escherichia coli. The full sequence of axeA was amplified by PCR. Sequence analysis of the PCR product revealed an open reading frame of 1,008 nucleotides encoding a protein consisted of 335 amino acid residues, with a calculated molecular mass of about 38 kDa. The base sequence showed 98% homology to the same gene of Streptomyces lividans. Two different kinds of acetyl xylan esterases were produced in Escherichia coli(pLacI) by IPTG induction; their molecular weights were 38 kDa and 34 kDa, respectively. Of these, 38 kDa protein seemed to be a total protein holding N-terminal signal peptide region, whereas 34 kDa protein seemed to be a matured protein without signal peptide which was produced by peptide bond cleavage between two amino acid residues of alanine 41 and alanine 42.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.1
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• pp.16-23
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• 1987

This experiment was conducted to determine the isozymic differences between normal maize and maize inbreds of multiple ears and tillers (MET). Two maize inbreds Euisung, Iri and their hybrid having tillers and multiple ears were compared with normal maize. With usual electrophoresis using 6% polyacrylamide gel, peroxidase and esterase enzymes were studied. Matured leaf, culm, leaf sheath, root and young ear tissues showed different isozymic patterns between METs and normal maize in peroxidase. The Euisung inbred grown for 7 days under dark condition showed typical peroxidase. bands compared with checks in the tissues of coleoptile and stele. Better observation of isozymic bands was made during early part of maize growth. Parental inbreds showed more active and apparent band differences than their hybrids in esterase. Bands for esterase were also apparently different in the stele, coleoptile and young ear tissues of the METs and the checks. The maize lines infected with black streaked dwarf virus showed obvious differences in peroxidase and esterase isozymes.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.3
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• pp.206-210
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• 2002

This study was carried out to investigate the genetic segregations and characteristics of off-type rice plants collected in Korea which were classified into seven groups based on grain characteristics. In the analysis of esterase electrophoresis, the long-grain red group was classified as 1 and 3 esterase isozyme zymogram(EIZ), the long-grain normal group was classified as 1, 3 and 7 EIZ. The extremely late sterility group was segregated variously as 1, 2, 1+2, 5, 6, 5+6, 7,8 ,7+8 and 12 EIZ. The long-grain red rice lines with 1 EIZ had a longer culm length and a lower length/width ratio to brown rice than the long-grain red rice lines with 3 EIZ. The long-grain normal rice lines with 3 EIZ had a longer culm length, shorter panicle length, greater number of tillers, lower length/width ratio of brown rice, and fewer number of grains per panicle than did the long-grain red rice lines with 1 or 7 EIZ.