• 한국미생물·생명공학회지
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• 제33권1호
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• pp.9-15
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• 2005

Chitin deacetylase(CDA; EC 3.5.1.41)는 키틴의 N-acetamide bonds를 가수분해하여 이를 키토산으로 전환시키는 효소다. 한편, 키토산은 의약, 화장품, 식품, 농업 등의 분야에서 다양하게 응용되는 고분자 다당류이다. 본 논문에서는 미생물 유래 CDA의 분포, 분석법, 효소적 특성, 기질 특이성, 작용기작, 유전자의 구조, 생물학적 역할, 응용 등의 최신 지견을 기술하고자 하였다. 미생물 CDA가 세포벽 형성과 식물-미생물 상호작용에 관여한다는 연구결과들을 제시하였으며, CDA의 유전자 구조를 다양한 acetylated poly/oligo-saccharides를 탈아세틸화하는 family 4 carbohydrate esterase의 유전자 구조와 비교하였다. 키틴의 탈아세틸화로 키토산을 제조하는 과정에 CDA의 활용 가능성과, CDA를 포함한 고활성의 키틴 대사효소들을 분비하는 곤충 병원균의 활용 가능성도 살펴보았다.

• Journal of Microbiology and Biotechnology
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• 제22권8호
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• pp.1044-1053
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• 2012

The gene encoding an esterase enzyme was cloned from a metagenomic library of cow rumen bacteria. The esterase gene (est5S) was 1,026 bp in length, encoding a protein of 366 amino acid residues with a calculated molecular mass of 40,168 Da. The molecular mass of the enzyme was estimated to be 40,000 Da. The Est5S protein contains the Gly-X-Ser-X-Gly motif found in most bacterial and eukaryotic serine hydrolases. However, the Asp or Glu necessary for the catalytic triad [Ser-Asp-(Glu)-His] was not present, indicating Est5S represents a novel member of the GHSQG family of esterolytic enzymes. BlastP in the NCBI database analysis of Est5S revealed homology to hypothetical proteins and it had no homology to previous known lipases and esterases. Est5S was optimally active at pH 7.0 and $40^{\circ}C$. Among the p-nitrophenyl acylesters tested, high enzymatic activities were observed on the short-chain p-nitrophenyl acylesters, such as p-nitrophenyl acetate, etc. The conserved serine residue ($Ser_{190}$) was shown to be important for Est5S activity. The primers that amplified the est5S gene did not show any relative band with 49 species of culturable rumen bacteria. This implies that a new group esterase gene, est5S, may have come from a noncultured cow rumen bacterium.

• Journal of Microbiology and Biotechnology
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• 제24권9호
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• pp.1260-1268
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• 2014

Screening of a gene library from Paenibacillus sp. PBS-2 generated in Escherichia coli led to the identification of a clone with lipolytic activity. Sequence analysis showed an open reading frame encoding a polypeptide of 378 amino acid residues with a predicted molecular mass of 42 kDa. The esterase displayed 69% and 42% identity with the putative ${\beta}$-lactamases from Paenibacillus sp. JDR-2 and Clostridium sp. BNL1100, respectively. The esterase contained a Ser-x-x-Lys motif that is conserved among all ${\beta}$-lactamases found to date. The protein PBS-2 was produced in both soluble and insoluble forms when E. coli cells harboring the gene were cultured at $18^{\circ}C$. The enzyme is a serine protein and was active against p-nitrophenyl esters of $C_2$, $C_4$, $C_8$, and $C_{10}$. The optimum pH and temperature for enzyme activity were pH 9.0 and $30^{\circ}C$, respectively. Relative activity of 55% remained at up to $5^{\circ}C$ with an activation energy of 5.84 kcal/mol, which indicates that the enzyme is cold-adapted. Enzyme activity was inhibited by $Cd^{2+}$, $Cu^{2+}$, and $Hg^{2+}$ ions. As expected for a serine esterase, activity was inhibited by phenylmethylsulfonyl fluoride. The enzyme was remarkably active and stable in the presence of commercial detergents and organic solvents. This cold-adapted esterase has potential as a biocatalyst and detergent additive for use at low temperatures.

• Journal of Microbiology and Biotechnology
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• 제24권6호
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• pp.771-780
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• 2014

A putative lipolytic enzyme gene, named as est9x, was obtained from a marine microbial metagenome of the South China Sea. Sequence analysis showed that Est9X shares lower than 27% sequence identities with the characterized lipolytic enzymes, but possesses a catalytic triad highly conserved in lipolytic enzymes of the ${\alpha}/{\beta}$ hydrolase superfamily. By phylogenetic tree construction, Est9X was grouped into a new lipase/esterase family. To understand Est9X protein in depth, it was recombinantly expressed, purified, and biochemically characterized. Within potential hydrolytic activities, only lipase/esterase activity was detected for Est9X, confirming its identity as a lipolytic enzyme. When using p-nitrophenol esters with varying lengths of fatty acid as substrates, Est9X exhibited the highest activity to the C2 substrate, indicating it is an esterase. The optimal activity of Est9X occurred at a temperature of $65^{\cric}C$, and Est9X was pretty stable below the optimum temperature. Distinguished from other salt-tolerant esterases, Est9X's activity was tolerant to and even promoted by as high as 4 M NaCl. Our results imply that Est9X is a unique esterase and could be a potential candidate for industrial application under extreme conditions.

• Environmental Analysis Health and Toxicology
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• 제6권3_4호
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• pp.105-121
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• 1991

The object of this study is to investigate the toxicity of fenvalerate [(RS)-$\alpha$-cyano-3 -phonoxybenzyl-(RS)-2-(4-ch1orophenyl)-3-methylbutyrate] and the effect of carbaryl on the toxicity of fenvalerate. Rats were treated with fenvalerate (50 mg/kg, 100 mg/kg), carbaryl (50 mg/kg, 100 mg/kg) or mixtures of the two compounds (fenvalerate+carbaryl: 50 mg/kg+50 mg/kg, 50 mg/kg+100 mg/kg) by oral administration for 1~3 weeks. Control groups were treated with corn oil. The experimental results were summarized as follows. 1. LD$_{50}$ values of fenvalerate and carbaryl in male rats were 385 mg/kg and 625 mg/kg respectively. When 50 mg/kg and 100 mg/kg of carbaryl were administratrd, LD$_{50}$values of fenvalerate were 265 mg/kg and 225 mg/kg respectively. 2. Biochemical parameters such as ALT, LDH and glucose in serum were much more increased in the groups treated with mixture than the groups treated with either one of fenvalerate or carbaryl. 3. The groups treated with carbaryl and mixture for 3 weeks, the contents of cytochrome P-450 in the liver were significantly increased. In renal microsomal fractions, however, no significant changes of drug metabolizing enzyme activities were observed. 4. The activities of aniline hydroxylase in hepatic microsomal fractions were increased in the groups treated with fenvalerate and mixture and activity was much more increased in the groups treated with mixture. 5. The activities of ATPase in the groups treated with fenvalerate were decreased than that of groups treated with mixture. TBA values and the activity of glucose-6 -phosphatase in the liver were not significantly changed. 6. In mixture treated groups, the activities of cholinesterase in serum and in the liver were more decreased than those of carbaryl treated groups. The activities of carboxylesterase in serum in the liver were slightly increased in mixture treated groups, but in fenvalerate treated groups, the activities of carboxylesterase were much more increased than those of control groups. 7. As a result of this study, when carbaryl was as the synergist of fenvalerate, carbaryl inhibited the activities of esterases, so the toxicity of fenvalerate was increased.sed.

• 미생물학회지
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• 제39권2호
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• pp.83-88
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• 2003

streptomyces coelicolor A3(2)의 acetyl xylan esterase 유전자를 Escherichia coli께 클로닝하여 그 발현양상을 조사하였다. 이를 위하여 유전자 전체 DNA를 PCR증폭을 통하여 제조하였다. PCR산물의 염기서열을 분석한 결과 1,008개의 nucleotide로 구성된 하나의 open reading frame이 존재함을 확인하였고, 이것은 335개의 아미노산으로 이루어진 약 38 kDa의 단백질을 생성할 것으로 예측할 수 있었다. 이 유전자의 염기 서열은 streptomyces lividans의 acetyl xylan esterase와 98%의 상동성을 가졌다. 그런데 Escherichia coli (pLacl)에서 IPTG유도에 의해 두가지의 acetyl xylan esterase가 발현되었으며 각각의 분자량은 38 kDa과 34 kDa이었다. 이중에서 38 kDa의 단백질은 N-말단의 signal peptide를 포함한 전체 단백질이고,34 kDa의 단백질은 41번과 42번의 두 알라닌 잔기사이의 펩티드 결합이 끊어져 생산된 것으로 추정되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제24권3호
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• pp.379-385
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• 2011

Ferulic acid esterase (FAE) and acetyl esterase (AE) cleave feruloyl groups substituted at the 5'-OH group of arabinosyl residues and acetyl groups substituted at O-2/O-3 of the xylan backbone, respectively, of arabinoxylans in the cell wall of grasses. In this study, the enzyme profiles of FAE, AE and polysaccharide hydrolases of the anaerobic rumen fungus Neocallimastix sp. YQ1 grown on Chinese wildrye grass hay (CW) or alfalfa hay (AH) were investigated by two $2{\times}4$ factorial experiments, each in 10-day pure cultures. The treatments consisted of two glucose levels ($G^+$: glucose at 1.0 g/L, $G^-$: no glucose) and four N sources (N1: 1.0 g/L yeast extract, 1.0 g/L tryptone and 0.5 g/L $(NH_4)_2SO_4$; N2: 2.8 g/L yeast extract and 0.5 g/L $(NH_4)_2SO_4$; N3: 1.6 g/L tryptone and 0.5 g/L $(NH_4)_2SO_4$; N4: 1.4 g/L tryptone and 1.7 g/L yeast extract) in defined media. The optimal combinations of glucose level and N source for the fungus on CW, instead of AH, were $G^-N4$ and $G^-N3$ for maximum production of FAE and AE, respectively. Xylanase activity peaked on day 4 and day 6 for the fungus grown on CW and AH, respectively. The activities of esterases were positively correlated with those of xylanase and carboxymethyl cellulase. The fungus grown on CW exhibited a greater volatile fatty acid production than on AH with a greater release of ferulic acid from plant cell wall.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2002년도 생물공학의 동향 (X)
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• pp.457-460
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• 2002

In an effort to isolate novel strains expressing a thermostable esterase that hydrolyzed the rac-ketoprofen ethyl ester to ketoprofen in the stereospecific manner, we screened various soils and composts from broad ecological niches in which the activity was expected to be found. Three hundreds of microbial strains were tested to determine their ester-hydrolyzing activity by using an agar plate containing insoluble tributyrin as an indicative substrate, and then further screened by activity on the (R,S)-ketoprofen ethyl ester. Twenty-six strains were screened primarily at high growth and incubation temperature and further compared the ability to ethyl ester-hydrolyzing activity in terms of conversion yield and chiral specificity. Consequently, a strain JYl44 was isolated as a novel strain that produced a (R)-stereospecific esterase with high stability and systematically identified as a Bacillus stearothermophilus JY144. The enzyme indeed stables at a broad range of temperature, upto 65 $^{\circ}C$, and pH ranging from 6.0 to 10.0. The optimal temperature and pH for enzymatic conversion were 50 $^{\circ}C$ and 9.0, respectively. Based on the observations that resulted a poor cell growth, and enzyme expression in wild type strain, we further attempted the gene cloning into a general host Escherichia coli and determined its primary structure, concomitantly resulting a high level expression of the enzyme. The cloned gene had an open reading frame (250 amino acids) with a calculated molecular mass of 27.4 kDa, and its primary structure showed a relative high homology (45-52 %) to the esterases from Streptomyces and Bacillus strains. The recombinant whole cell enzyme could efficiently convert the rac-ketoprofen ethyl ester to (R)-ketoprofen, with optical purity of 99 % and yield of 49 %.

• Journal of Microbiology and Biotechnology
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• 제14권1호
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• pp.97-104
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• 2004

Water-sludge bacteria were screened to find a lipase enantioselectively hydrolyzing itraconazole precursor, which is well known as the starting material of antifungal drug agents. A bacterial strain was isolated and identified as Acinetobacter junii SY-01. After the strain was cultivated, the enzyme was purified 39.4-fold using ultrafiltration and gel filtration through a Sephadex G-100 chromatographic column and the activity yield was 34.9%. The molecular weight of the enzyme was about 40 kDa, as measured by SDS-PAGE, and the optimum pH was 7.0- 9.0 and stable at pH 6.0- 9.0. The optimum temperature was 45- $5^{\circ}C$, and 73% of the enzymes activity remained after incubation at 70% for 1 h. Enzyme activity was enhanced by gall powder, sodium deoxycholate, a cationic detergent Tween 80, and a non-ionic detergent Triton X-100, but was markedly inhibited by metal ions such as $Hg^{2＋},Cu^{2＋},Ni^{2＋}/,Ca^{2＋}$, and an anionic-surfactant sodium dodecylsulfate. The $K_{m}$ values for (R)- and (S)-enantiomers of the itraconazole precursor were 0.385 and 21.83 mM, respectively, and the $V_{max} values ($\mu$Mㆍmin^{-1}.)$ were 6.73 and 6.49, respectively. The acetyl group among the different acyl moieties of itraconazole precursor showed the highest enantioselectivity for the hydrolysis by the Acinetobacter junii SY-01 lipase, and the lipase from Acinetobacter junii SY-01 displayed better enantioselectivity than that of commercially available lipases and esterases.

• Journal of Pharmaceutical Investigation
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• 제37권1호
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• pp.45-49
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• 2007

Dextran-5-aminosalicylic acid conjugate (dextran-5-ASA) was in vitro-evaluated as a polymeric colon-spe-cific prodrug of 5-aminosalicylic acid (5-ASA). Chemical stability of dextran-5-ASA in the pH 1.2 or 6.8 buffer solutions was investigated at 37 for 6 hrs. The dextran backbone was not degraded and no 5-ASA release was detected. Moreover, dextran-5-ASA neither liberated 5-ASA in the homogenates of the small intestine of rats nor was transported across Caco-2 cell monolayers, suggesting no significant loss of dextran-5-ASA during transit through the upper intestine. Furthermore, incubation of dextran-5-ASA in 10% cecal contents of rats released about 37% and 55% of 5-ASA bound to dextran in 8 hr and 24 hr, respectively. While that with either esterase or dextranase failed to liberate 5-ASA from the polymeric prodrug, incubation of dextran-5-ASA with both esterases and dextranse released 5-ASA up to about 24% of 5-ASA bound to dextran. These results suggest that, after oral administration of dextran-5-ASA, the polymeric prodrug is delivered specifically to and releases 5-ASA in the large intestine, and reveal that the 5-ASA release by cleavage of the ester bond requires precedent depolymerization of the dextran backbone.