• 한국독성학회:학술대회논문집
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• 한국독성학회 2003년도 추계학술대회
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• pp.184-184
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• 2003

ENU(ethylnitrosourea) mutagenesis has been carrying out since 1999 in Korea Institute of Toxicology (KIT), Korea Research Institute Chemical of Technology (KRlCT). We have chosen BALB/c and C57BL/6 and screened for dominant and recessive mutants. Four hundred and twenty one males(GO) have been injected with ENU, 150, 200, 250 and 300 mg/kg body weight, twice, one week apart.(omitted)

• Bulletin of the Korean Chemical Society
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• 제27권6호
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• pp.819-820
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• 2006

• Bulletin of the Korean Chemical Society
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• 제32권12호
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• pp.4427-4430
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• 2011

• Bulletin of the Korean Chemical Society
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• 제28권6호
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• pp.907-908
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• 2007

• Journal of Plant Biotechnology
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• 제37권2호
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• pp.115-124
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• 2010

As the completion of genome sequencing, large collection of expression data and the great efforts in annotating plant genomes, the next challenge is to systematically assign functions to all predicted genes in the genome. Functional genome analysis of plants has entered the high-throughput stage. The generations and collections of mutants at the genome-wide level form technological platform of functional genomics. However, to identify the exact function of unknown genes it is necessary to understand each gene's role in the complex orchestration of all gene activities in the plant cell. Gene function analysis therefore necessitates the analysis of temporal and spatial gene expression patterns. The most conclusive information about changes in gene expression levels can be gained from analysis of the varying qualitative and quantitative changes of messenger RNAs, proteins and metabolites. New technologies have been developed to allow fast and highly parallel measurements of these constituents of the cell that make up gene activity. We have reviewed currently employed technologies to identify unknown functions of predicted genes including map-based cloning, insertional mutagenesis, reverse genetics, chemical mutagenesis, microarray analysis, FOX-hunting system, gene silencing mutagenesis, proteomics and chemical genomics. Recent improvements in technologies for functional genomics enable whole-genome functional analysis, and thus open new avenues for studies of the regulations and functions of unknown genes in plants.

• Journal of Microbiology and Biotechnology
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• 제16권6호
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• pp.974-978
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• 2006

The cytochrome P450 monooxygenase from the pikromycin biosynthetic gene cluster in Streptomyces venezuelae, known as PikC, was observed to hydroxylate the unnatural substrate indole to indigo. Furthermore, the site-directed mutagenesis of PikC monooxygenase led to the mutant enzyme F171Q, in which Phe171 was altered to Gln, with enhanced activity for the hydroxylation of indole. From enzyme kinetic studies, F171Q showed an approximately five-fold higher catalytic efficiency compared with the wild-type PikC. Therefore, these results demonstrate the promising application of P450s originating from Streptomyces, normally involved in polyketide biosynthesis, to generate a diverse array of other industrially useful compounds.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2003년도 정기총회 및 학술발표회
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• pp.70-70
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• 2003

Active sites and substrate bindings of 1-aminoxyclopropane-1-carboxylate oxidase (MD-ACO1) catalyzing the oxidative conversion of ACC to ethylene have been determined based on site-directed mutagenesis and comparative modeling methods. Molecular modeling based on the crystal structure of Isopenicillin N synthase (IPNS) provided MD-ACO1 structure. MD-ACO1 protein folds into a compact jelly roll shape, consisting of 9 ${\alpha}$-helices, 10 ${\beta}$-strands and several long loops. The MD-ACO1/ACC/Fe(II)/Ascorbate complex conformation was determined from automated docking program, AUTODOCK. The MD-ACO1/Fell complex model was consistent with well known binding motif information (HIS177-ASP179-HIS234). The cosubstrate, ascorbate is placed between iron binding pocket and Arg244 of MD-ACO1 enzyme, supporting the critical role of Arg244 for generating reaction product. These findings are strongly supported by previous biochemical data as well as site-directed mutagenesis data. The structure of enzyme/substrate suggests the structural mechanism for the biochemical role as well as substrate specificity of MD-ACO1 enzyme.

• Bulletin of the Korean Chemical Society
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• 제28권5호
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• pp.772-776
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• 2007

In order to study the role of residue in the active site of glutathione S-transferase (GST), Arg13 residue in human GST P1-1 was replaced with alanine, lysine and leucine by site-directed mutagenesis to obtain mutants R13A, R13K and R13L. These three mutant enzymes were expressed in Escherichia coli and purified to electrophoretic homogeneity by affinity chromatography on immobilized GSH. Mutation of Arg13 into Ala caused a substantial reduction of the specific activity by 10-fold. Km GSH, Km DCNB and Km EPNP values of R13A were approximately 2-3 fold larger than those of the wild type. Mutation of Arg13 into Ala also significantly affected I50 values of S-methyl-GSH that compete with GSH and ethacrynic acid, an electrophilic substrate-like compound. These results appeared that the substitution of Arg13 with Ala resulted in significant structural change of the active site. Mutation of Arg13 into Leu reduced the catalytic activity by approximately 2-fold, whereas substitution by Lys scarcely affected the activity, indicating the significance of a positively charged residue at position 13. Therefore, arginine 13 participates in catalytic activity as mainly involved in the construction of the proper electrostatic field and conformation of the active site in human GST P1-1.

• BMB Reports
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• 제28권4호
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• pp.363-367
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• 1995

E. coli methionyl-tRNA synthetase is one of the class I tRNA synthetases. The Tryptophane residue at the position 461 located in the C-terminal domain of the enzyme is a key amino acid for the interaction with the anticodon of $tRNA^{Met}$. W461 was replaced with other amino acids to determine the chemical requirement for the interaction with the anticodon of $tRNA^{Met}$. Saturation mutagenesis at the position 461 generated a total of 12 substitution mutants of methionyl-tRNA synthetase. All the mutants showed the same in vivo stability as the wild-type enzyme, suggesting that the amino acid substitutions did not cause severe conformational change of the protein The mutants containing tyrosine, phenylalanine, histidine and cysteine substitutions showed in vivo activity while all the other mutants did not. The comparison of the in vitro aminoacylation activities of these mutants showed that aromatic ring structure, Van der Waals volume and hydrogen bond potential of the amino acid residue at the position 461 are the major determinants for the interaction with the anticodon of $tRNA^{Met}$.

• Advances in environmental research
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• 제2권3호
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• pp.245-260
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• 2013

Biosorption represents a technological innovation as well as a cost effective excellent remediation technology for cleaning up radionuclides from aqueous environment. In the present study, a bacteria strain FB12 with high adsorption rate of uranium ion was isolated from the vicinity of the nuclear power plant. It was tentatively identified as Bacillus sp.FB12 according to the 16S rDNA sequencing. Efforts were made to further improve the adsorption rate and genetic stability by UV irradiation and UV-LiCl cooperative mutagenesis. The improved strain named Bacillus sp.UV32 obtains excellent genetic stability and a high adsorption rate of 95.9%. The adsorption of uranium U (VI) by Bacillus sp.UV32 from aqueous solution was examined as a function of metal ion concentration, cell concentration, adsorption time, pH, temperature, and the presence of some foreign ions. The adsorption process of U (VI) was found to follow the pseudo-second-order kinetic equation. The adsorption isotherm study indicated that it preferably followed the Langmuir adsorption isotherm. The thermodynamic parameters values calculated clearly indicated that the adsorption process was feasible, spontaneous and endothermic in nature. These properties show that Bacillus sp.UV32 has potential application in the removal of uranium (VI) from the radioactive wastewater.