Seok SH

References (4)

Title : Crystal structure and characterization of esterase Est25 mutants reveal improved enantioselectivity toward (S)-ketoprofen ethyl ester - Kim_2017_Appl.Microbiol.Biotechnol_101_2333
Author(s) : Kim J , Seok SH , Hong E , Yoo TH , Seo MD , Ryu Y
Ref : Applied Microbiology & Biotechnology , 101 :2333 , 2017
Abstract : Esterases comprise a group of enzymes that catalyze the cleavage and synthesis of ester bonds. They are important in biotechnological applications owing to their enantioselectivity, regioselectivity, broad substrate specificity, and the fact that they do not require cofactors. In a previous study, we isolated the esterase Est25 from a metagenomic library. Est25 showed catalytic activity toward the (R,S)-ketoprofen ethyl ester but had low enantioselectivity toward the (S)-ketoprofen ethyl ester. Because (S)-ketoprofen has stronger anti-inflammatory effects and fewer side effects than (R)-ketoprofen, enantioselectivity of this esterase is important. In this study, we generated Est25 mutants with improved enantioselectivity toward the (S)-ketoprofen ethyl ester; improved enantioselectivity of mutants was established by analysis of their crystal structures. The enantioselectivity of mutants was influenced by substitution of Phe72 and Leu255. Substituting these residues changed the size of the binding pocket and the entrance hole that leads to the active site. The enantioselectivity of Est25 (E = 1.1 +/- 0.0) was improved in the mutants F72G (E = 1.9 +/- 0.2), L255W (E = 16.1 +/- 1.1), and F72G/L255W (E = 60.1 +/- 0.5). Finally, characterization of Est25 mutants was performed by determining the optimum reaction conditions, thermostability, effect of additives, and substrate specificity after substituting Phe72 and Leu255.
ESTHER : Kim_2017_Appl.Microbiol.Biotechnol_101_2333
PubMedSearch : Kim_2017_Appl.Microbiol.Biotechnol_101_2333
PubMedID: 27915377
Gene_locus related to this paper: 9bact-q4tzq3

Title : Whole-Genome Sequence of a Novel Species, Mycobacterium yongonense DSM 45126T - Kim_2013_Genome.Announc_1_e00604
Author(s) : Kim BJ , Kim BR , Lee SY , Seok SH , Kook YH
Ref : Genome Announc , 1 : , 2013
Abstract : Here, we report the complete genome sequence of Mycobacterium yongonense DSM 45126(T), genetically closely related to the INT5 genotype of M. intracellulare.
ESTHER : Kim_2013_Genome.Announc_1_e00604
PubMedSearch : Kim_2013_Genome.Announc_1_e00604
PubMedID: 23929490
Gene_locus related to this paper: mycia-h8ivh5 , 9myco-j9waw2 , mycia-h8iug5 , 9myco-i2acb5

Title : Complete Genome Sequence of Mycobacterium massiliense Clinical Strain Asan 50594, Belonging to the Type II Genotype - Kim_2013_Genome.Announc_1_e00429
Author(s) : Kim BJ , Kim BR , Hong SH , Seok SH , Kook YH
Ref : Genome Announc , 1 : , 2013
Abstract : We report the complete genome sequence of the Mycobacterium massiliense clinical strain Asan 50594, which was grouped into the M. massiliense type II genotype, isolated from a Korean patient. This genome sequence will serve as a valuable reference for understanding the disparity in virulence and epidemiological traits between strains belonging to the Mycobacterium abscessus complex.
ESTHER : Kim_2013_Genome.Announc_1_e00429
PubMedSearch : Kim_2013_Genome.Announc_1_e00429
PubMedID: 23833135
Gene_locus related to this paper: mycab-b1mch4 , mycab-b1mdu3 , mycab-b1mes2 , mycab-b1mes3 , mycab-b1mfj3 , mycab-b1mgd3 , mycab-b1mkl9 , mycab-i9cu79 , myca9-b1miq0 , mycab-r4v1a9

Title : Risk assessment of the organophosphate pesticides isazofos and pyraclofos using a 21-day dietary toxicity study in Japanese quail - Seok_2008_Ecotoxicol.Environ.Saf_71_245
Author(s) : Seok SH , Park JH , Cho SA , Kim DJ , Bae BK
Ref : Ecotoxicology & Environmental Safety , 71 :245 , 2008
Abstract : Six-week-old male and female Japanese quails (Coturnix japonica) received two organophosphate pesticides, isazofos and pyraclofos, for a 21-day dietary toxicity test, based on the OECD workshop report. During the treatment period, body weight and food consumption of the quail decreased with exposure to either isazofos or pyraclofos. Using the up-and-down procedure to determine the 50% mortality value, we found that the 21-day LC(50) of isazofos and pyraclofos were 40 and 87 mg/kg body weight, respectively. Ataxia, salivation, diarrhea, ruffled feathers, and convulsions at a dead point were observed with both pesticides. The tips of the villi were necrotic in the high dosage groups of isazofos- and pyraclofos-treated quail. Based on these results, body weight, food consumption, clinical signs, and histopathological findings may be useful parameters for detecting the dietary toxicity associated with isazofos and pyraclofos exposure. In addition, Japanese quail could be an excellent bird model for monitoring the toxicological risks of pesticides in Korea.
ESTHER : Seok_2008_Ecotoxicol.Environ.Saf_71_245
PubMedSearch : Seok_2008_Ecotoxicol.Environ.Saf_71_245
PubMedID: 17629558