• Journal of Microbiology
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• v.45 no.2
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• pp.175-178
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• 2007

An endonuclease from Xanthomonas oryzae pathovar oryzae KACC 10331, XorII, was recombinantly produced in Escherichia coli using a T7 system. XorII was purified using a combination of ion exchange and immobilized metal affinity chromatography (IMAC). An optimized washing protocol was carried out on an IMAC in order to obtain a high purity product. The final amount of purified XorII was approximately 2.5 mg/L of LB medium. The purified recombinant XorII was functional and showed the same cleavage pattern as PvuI. The enzyme activity tested the highest at $25^{\circ}C$ in 50 mM NaCl, 10 mM Tris-HCl, 10 mM $MgCl_{2}$, and 1 mM dithiothreitol at a pH of 7.9.

• Microbiology and Biotechnology Letters
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• v.21 no.4
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• pp.299-305
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• 1993

Numerical identification was carried out for an isolate of Streptomyces D2-5 producing a new restriction endonuclease Svi I. Fifty taxonomic unit characters were tested and the data were analyzed numerically using the TAXON program. The isolate was best matched to Streptomyces violochromogenes in the major cluster 18 of Streptomyces. Therefore, it was concluded that the isolate was identified to be a member of Streptomyces violochromogenes.

• Proceedings of the Microbiological Society of Korea Conference
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• 2004.05a
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• pp.47-50
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• 2004

The defenses against free radical damage include specialized repair enzymes that correct oxidative damages in DNA, and detoxification systems such as superoxide dismutases. These defenses may be coordinated genetically as global responses. We hypothesized that the expression of the SOD and the DNA repair genes would inhibit DNA damage under oxidative stress. Therefore, the protection of E. coli mutants deficient in SOD and DNA repair genes $(sod^-\;xth^-\;and\;nfo^-)$ was demonstrated by transforming the mutant strain with a plasmid pYK9 which encoded Photobacterium leiognathi CuZnSOD and human AP endonuclease. The results show that survival rates were increased in $sod^+\;xth^-\;nfo^+$ cells compared to $sod^-\;xth^-\;ap^+,\;sod^-\;xth^-\;ap^-,\;and\;sod^+\;xth^-\;ap^-$ cells under oxidative stress generated from 0.1 mM Paraquat or 3 mM $H_2O_2$. The data suggested that, at least, SOD and DNA repair enzymes may have collaborate protection and repair of the damaged DNA. Additionally, both enzymes are required for protection against free radicals.

• BMB Reports
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• v.29 no.1
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• pp.17-21
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• 1996

Ile91 of restriction endonuclease EcoRV, which has not been known to take part directly in catalytic activity, was substituted with Leu by site-directed mutagenesis. The Ile91Leu mutant shows over 1000-fold less activity than the wild type EcoRV under standard reaction condition. The metal ion dependency of the reaction was altered. In contrast to the wild type EcoRV, the mutant prefers $Mn^{2+}$ to $Mn^{2+}$ as the cofactor. In $Mn^{2+}$ buffer the mutant is as active as the wild type enzyme in $Mn^{2+}$ buffer. Like the wild type enzyme, the mutant shows an unspecific binding of DNA in gel shift experiments. In contrast to the wild type enzyme, the mutant did not cleave at noncognate sites of DNA under star condition.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1993.04a
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• pp.137-137
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• 1993

방사선, 자외선, 화학물질 등 여러 변이원에 의해 생긴 DNA 손상의 대부분은 생체내에 존재하는 효소들에 의해 수복(repair)되어 DNA는 안정하게 유지된다. T$_4$ phage 유래의 T$_4$ endonuclease V는 자외선에 의해 DNA에 pyrimidine dimer가 생겼을때 이것을 특이적으로 절제 수복하는 효소이다. 인간의 질환인 색소성 걸피증(Xeroderma pigmentosum)은 태양광선, 특히 자외선에 의해 고빈도로 피부암을 발생한다. 이 질환은 유전적으로 DNA 수복기구에 장애가 있기 때문에 일어난다. 색소성 건피증의 배양세포에 T$_4$ endonuclease V를 도입하면 세포의 DNA 수복능력이 회복되기 때문에 인간과 phage라는 서로 멀리 떨어진 생물종에 공통의 DNA 수복기구가 존재하고 있다는 것을 알 수 있다.

• The Journal of the Korean Society for Microbiology
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• v.22 no.4
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• pp.463-471
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• 1987

The genomes of leptospiral field isolates from Korea belonging to serogroup Icterohaemorrhagiae (21 strains) and serogroup Canicola (1 strain) were analysed and compared by restriction enzyme analysis with EcoRI and HindIII as digesting enzymes. One isolate belonging to serogroup Canicola showed the same pattern as serovar portlandvere. All 21 isolates belonging to serogroup Icterohaemorrhagiae showed almost same patterns as Leptospira serovar lai from China, But with very slight differences 21 isolates could be classified into 8 subtypes and these grouping seems to reflect the differences in epidemiological niche. And also the geographical data consisted with the grouping into 8 subtypes. According to our results, we concluded that the restriction endonuclease analysis of chromosomal DNA will be an accurate and reliable method to compare and classify pathogenic leptospires.

• Microbiology and Biotechnology Letters
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• v.22 no.2
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• pp.126-133
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• 1994

Numerical identification was aplied for Streptomyces sp.264, an isolate producing a new restriction endonuclease Sdi I. The restriction enzyme would appear to be an isoschisomer of Xho I. Fifty taxonomic unit characters were tested and the data obtained were analyzed numerically by using the TAXON program. The isolate was identified to be the major cluster 19 of Streptomyces and best matched to S. diastatochromogenes. It was, therefore, concluded that the isolate was identified to be a member of Streptomyces diastatochromogenes.

• Journal of Microbiology and Biotechnology
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• v.5 no.5
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• pp.269-273
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• 1995

A thermotolerable restriction endonuclease. Svil, found in Streptomyces violochromogenes D2-5 was purified. For the purification, streptomycin sulfate and ammonium sulfate precipitation was used. Ph osphocellulose P-ll, DEAE-Cellulose and Sephacryl-S200 HR colum chromatography were also performed. The purified enzyme was found to be homogeneous and the molecular weight of the enzyme estimated by polyacrylamide gel electrophoresis containing 0.1$%$ SDS was about 32, 000 daltons. The recognition sequence and cleavage site of the enzyme were determined to be $5^1$-$TT\downarrow CGAA$-$3^1$ which is the same sequence as that of Asull. Unlike Asull, however, the Svil shows high thermal stability.

• Proceedings of the Korean Biophysical Society Conference
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• 1996.07a
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• pp.18-18
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• 1996

Bacteriophage T4 endonuclease V initiates the repair of ultraviolet (UV)-induced pyrimidine dimer photoproducts in duplex DNA. The mechanism of DNA strand cleavage involves four sequential steps: linear diffusion along dsDNA, pyrimidine dimer-specific binding, pyrimidine dimer-DNA glycosylase activity, and AP lyase activity. (omitted)

• BMB Reports
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• v.31 no.2
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• pp.149-155
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• 1998

The N199H variant of the EcoRI endonuclease has about twice the catalytic activity of the wild-type. A comparison of their biochemical characteristics, using synthetic oligonucleotides 5'-dAAAACTTAAGAAAAAAAAAAA-3' (KA) and 5'-dTTTTTGAATTCTTTTTTTTTT-3' (KT), helps to define the cleavage reaction pathway of these enzymes. Both EcoRI and EcoRI variant N199H were found to cleave singlestranded KA or KT about three times faster than the double-stranded forms, although the KT oligonucleotide was more susceptible. Using the ssDNA substrate in kinetic analyses, lower $K_m$ values were obtained for the N199H variant than for the wild-type at low (50 mM), as well as high (200 mM), sodium chloride concentrations. This difference between the endonucleases is attributed to a grealter accessibility for tbe substrate by the variant, and also a higher affinity for the DNA backbone. It also appears that the relative activities of the two enzymes, particularly at high ionic strength, are proportional to their populations in the monomeric enzyme form. That is, according to gel filtration data, half of the N199H molecules exist as monomers in 200 mM NaCl, whereas those of the wild-type are mainly dimeric. Consequently, the Asp199 residue of the EcoRI endonuclease may be implicated in the protein-protein interaction leading to dimerization, as well as in coupling to DNA substrates. In summary, it is proposed that active monomeric endonuclease molecules, derived from the dimeric enzyme, recognize and form a complex with a single stranded form of the DNA substrate, which then undergoes nucleophilic substitution and cleavage.