백서 재생간의 DNA topoisomerase Ⅰ 에 관한 연구

권기량,임규,황병두 충남대학교 의과대학 지역사회의학연구소 1991 충남의대잡지 Vol.18 No.1

The study was performed to evaluate changes of activity of DNA topoisomerase I that controls and modifies the topological state of DNA according to postoperative days after partial hepatectomy. The results of this experimental study were summarized as follows : 1. The liver mass doubles during the first 48 hours, and the rate of regeneration is greatest between first and second days after partial hepatectomy. 2. 25% of enzyme activity was increased in the first 12 hours in comparison with that of control after partial hepatectomy. The second days showed maximal increment. 200% in comparison with that of control. Later, enzyme activity was decreased till the seventh days after partial hepatectomy. 3. DNA Topo I was inhibited very slightly be camptothecin but 50% of enzyme activity was inhibited at 50μM of 10-hydroxycamptothecin. 4. In the case of spermine. 0.1mM. Complex formation was highest as 0.1mM spermine. 5. The enzyme shows a pH optimum around 6.4, but enzyme activity is seen within a broad range between pH 5.8 and 9.0. 6. The enzyme is completely inactivated by heat treatment for 5 minutes at 50℃. 7. 2mM Mg^2+ activates the enzyme activity over 3-folds. Cu^2+, Zn^2+ completely inhibit it and Mn^2+, Co^2+, and Se^2+ inhibit upto 40%, 40% and 60% at 2mM respectively. 8. There was no sighificant difference between resection and regeneration liver. These results suggested that the role of DNA topoisomerase I is related to 2nd peak of DNA synthesis in regeneration of liver after partial hepatectomy.

Tubulin Polymerization에 대한 Podophyllotoxin의 영향

이성민,권기량,임규,황병두 충남대학교 의과대학 지역사회의학연구소 1991 충남의대잡지 Vol.18 No.1

Although the inhibition of microtubule assembly by podophyllotoxin is well established, the mediatory effect of some microtubule associated proteins for inhibition by podophyllotoxin is not clear. The microtubule(MADBP^+) was prepared from rabbit brain through 2 cycles of polymerization-depolymerization and the tubulin without DNA binding protein(MADBP^-) was prepared from MADBP^+ using double strand DNA-cellulose column chromatography and the properties of these tubulin preparation were compared with those of MADBP^+ being sigmoidal and MADBP^- being hyperbolic. MADBP^+ polymerization could he inhibited by podophyllotoxin, whereas MADBP^- polymerization could not. In the various concentration of podophyllotoain, there was little difference in colchicine binding activity between MADBP^- and MADBP^-. In the 2μM concentration of podophyllotoxin, the colchicine binding to MADBP^+ and MADBP^- were competitively inhibited with same extension. From the above results, the possible existence of some proteins which mediates the inhibitory effect of podophyllotoxin for tubulin polymerization was discussed.

사람 대장조직 DNA Topoisomerase I 에 관한 연구

오수정,권기량,임규,황병두 충남대학교 의과대학 지역사회의학연구소 1991 충남의대잡지 Vol.18 No.2

DNA topoisomerase I was prepared from normal mucosa and cancer tissue of human colon and the properties were compared. Specific activity of the enzyme from normal mucosa was 257.2 unit/mg protein/ min and that from cancer tissue was 403 unit/mg protein/min. Both enzymes showed a broad pH optimum from pH 5.8 to pH 7.4 and arc heat-labile, being completely inactivated by heat treatment at 55℃ for 5 minutes. The enzyme from normal mucosa was activated 0.2 M K^+ and 0.15 M Na^+ approximately 20 and 4 folds and that from cancer tissue was activated approximately 40 and 10 folds, respectively. Mg^2+ was the most potent activator, the enzyme from normal mucosa being 5, 20, and 60 folds activated at 2 mM, 10 mM, and 20 mM, respectively and the enzyme from cancer tissue being 2.5, 13, 26 folds activated, respectively. Both enzymes were inhibited by 2 mM ATP and 5 mM GTP in the presence of Mg^2+ and K^+ , respectively. ddATP and ddGTP were the potent inhibitors of these enzymes. The enzvate front nurmal mucosa was activated by spermine, spermidine, and histone H3 and that from cancer tissue was activated by histone H1. The enzyme from normal mucosa yeas completely inactivated by alkaline phosphatase treatment whereas the enzyme activity from cancer tissue was indifferent. The molecular weight of both enzymes were 150 KD. Camptothecin and 10-OH-camptothecin variably inhibited DNA relaxation according to tile enzyme preparation and there was no DNA fragmentation in the cleavage assay. From the above results, the possible role of phosphorylation for regulation of this enzyme and the application of camptothecin to colon cancer were discussed.

가토 뇌 Protein Methylase Ⅱ에 관한 연구

이창래,권기량,임규,황병두 충남대학교 의과대학 지역사회의학연구소 1990 충남의대잡지 Vol.17 No.2

Protein methylase II has been purified from rabbit brain approximately 1,600 folds with a 6% yield by the methods of homogenation, (NH_4)_2SO_4 saturation, S-adenosyl-L-homocysteine sepharose 4B column chromatography and hydroxyapatite column chromatography. The enzyme shows a pH optimun around 6. The enzyme is easily inactivated by heat treatment for 5 minutes at 60℃, and when stored at -20℃ in the presence of 10% glycerol, 40% of activity has been lost in a week. Fe^2+ and Se activate this enzyme upto 16% and 22% at 2mM concentration and Ni, Zn^2+ and Cu^2+ inhibit upto 17%, 32%, 100% at 2mM respectively. The inhibition by 250μM Cu^2+ is completely recovered by 2.5mM DTT and 40% recovered by 300μM DEDTC. The apparent Km value for S-adenosyl-L-methionine was 2.2 x 10 exp (-6)M and kinetic analysis of this enzyme in the presence of 30μM cupper ion shows that the nature of the inhibition to the enzyme is noncompetitive.

Tubulin Polymerization에 대한 Microtubule Associated DNA Binding Protein 의 영향

박희찬,권기량,황병두 충남대학교 의과대학 지역사회의학연구소 1989 충남의대잡지 Vol.16 No.2

Although the involvement of tubulin in the segregation of chromosome during mitosis is well established, the role of DNA binding protein(DBP) in tubulin polymerization is unclear. When the microtubule was prepared from rabbit brain through 2 cycle of glycerol-and GTP-mediated polymerization, the preparation(MADBP^+) was found to have serveral DBP. These DBP were separated from tubulin using double strand DNA cellulose column chromatography and the proper-ties of this tubulin polymerizatin could be inhibited by DNA whereas MADBP^- polymerization could not. Addition of microtubule associated DNA binding protein(MADBP) to MADBP^- could change MA-DBP^- polymerization kinetics; some MADBP fractions decreased the initiation and increased the elongation, some fractions simply increased the polymerization. From the above results, the possible roles of MADBP and possible binding site of taxol were discussed.

Tubulin Polymerization에 대한 Colchicine의 영향

최병훈,권기량,임규,황병두 충남대학교 의과대학 지역사회의학연구소 1990 충남의대잡지 Vol.17 No.2

Although the inhibition of microtubule assembly by colchicine is well established, the paradoxical effect of colchicine in the centriole, cilia and basal body is not clear. The microtubule(MADBP^+) was prepared from rabbit brain through 2 cycles of glycerol-and GTP-mediated polymerization and the tubulin without DNA binding protein(MADBP^-) was prepared from MADBP^+ using double strand DNA column chromatography and the properties of these tubulin preparation were compared with those of MADBP^+. The time course of tubulin polymerization was different, with MADBP^+ being sigmoidal and MADBP^- being hyperbolic. MADBP^+ polymerization could be inhibited by colchicine, whereas MADBP^- polymerization could not. There was little difference in colchicine binding activity between MADBP^+ and MADBP^- and the initial binding velocity of MADBP^- was faster than MADBP^-. From the above results, the possible existence of colchicine sensitive protein among microtubule associated DNA binding proteins was discussed.

가토뇌 Microtubule의 효소적 Carboxylmethylation이 Microtubule 기능 및 성상에 미치는 영향

곽명헌,권기량,임규,황병두 충남대학교 의과대학 지역사회의학연구소 1991 충남의대잡지 Vol.18 No.2

Microtubule purfied from rabbit brain by 2 cycles of polymerization and depolymerization in the presence of 2 mM GTP and 20% glycerol was carboxyl methylated by a purified protein methylase Ⅱ of rabbit brain, and changes in the properties of microtubule by carboxylmethylation were inverstigated. Tubulin and microtubule associated proteins were endogenously and exogenously carboxelmethvlated by protein methylase Ⅱ in a rate of 28.6 and 71.7 pmoles of methyl group incorporated into 1 mg protein for 15 minutes, respectively. Microtubule was found to be a better substrate than histone for this enzyme. Microtubule carboxylmethylation by protein methylase Ⅱ was activated 8%, 16% , 6%, 15% and 34% by 2 mM GDP, 2 mM Mg^2+, 2 mM Ca^2+, 40 μM colchicine and 40 μM podophyllotoxin, respectively. The binding of colchicine and Ca^2+ to microtubule were slightly enhanced by carboxylmethlated of microtubule. Polymerization kinetics of carhoxvlmethylated and noncarhuxylmethylated microtubule were similar. The inhibitory action of colrhicine and Ca^2+ on the microtubule polymerization was potentiated by carboxylnethylation of microtubule. These results were discussed with regard to the possible role of protein carboxylmethylation by protein methylase Ⅱ in the regulation of microtubule function.

HL-60 세포 분화유도증 c-Myc 발현에 대한 세포분화유도제의 영향

이용진,곽상태,김계영,이명선,권기량,임규,황병두 충남대학교 의과대학 지역사회의학연구소 1993 충남의대잡지 Vol.20 No.2

Effects of the differentiation inducers on DNA synthesis and c-myc gene expression have been investigated during the differentiation of human promyelocytic leukemia cell line HL-60. All-trans retinoic acid(retinoic acid) and dimethyl sulfoxide(DMSO) decreased DNA synthesis at 24 hours and 12-O-tetradecanoylphorbol 13-acetate(TPA) decreased at 12 hours after exposure, respectively. On the other hand control, no adding differentiation inducers, gradually increased DNA synthesis. The c-myc mRNA was sharply reduced at 24 hours in retinoic acid-, at 4 hours in DMSO-, and at 1 hour in TPA-exposured HL- 60 cells. The level of c-myc mRNAs was reduced in proportion to the concentration in all of three differentiation inducers. The level of c-myc mRNAs in the differentiation inducers-exposured cells were elevated by cycloheximide treatment. These results suggest that c-myc gene expression and differentiation mechanism are variable according to the kinds of the differentiation inducers in HL-60 cells.

All-Trans Retinoic Acid에 의한 HL-60 세포 분화유도중 H2B Histone, c-Myc 및 DNA Topoisomerase I 발현에 관한 연구

임규,박정동,최병한,이용진,김계영,이명선,장은미,김삼용,권기량,곽상태,황병두 忠南大學校 癌共同硏究所 1998 癌共同硏究所 硏究誌 Vol.2 No.1

Effects of all-trans retinoic acid(retinoic acid) on DNA replication, H2B histone and DNA topoisopmerase I(Topo I) gene expression have been investigated in human promyelocytic leukemia cell line HL-60. DNA synthesis decreased at 24 hours after exposure of retinoic acid in the HL-60 cells. H2B histone mRNA rapidly reduced at 48 hours and Topo I and c-myc mRNA at 24 hours in retinoic acid-exposured HL-60 cells, respectively. The levels of c-myc, H2B histone and Topo I gene expression were reduced in proportion to the concentration of retinoic acid. The H2B histone mRNA in retinoic acid-exposured cells was elevated by cycloheximide treatment, while the level of Topo I mRNA was constant. These results suggest that regulations of H2B histone, c-myc and Topo I gene expression are different from one another, and repression of Topo I gene is closely correlated with c-myc gene during retinoic acid-induced differentiation of HL-60 cells.

Fast Screening of Harmful Disinfectants in Household Products via Low-Temperature Plasma Ionization-Mass Spectrometry

( Hyoung Jun Lee ),( Gi Ryang Kweon ),( Yong-hyeon Yim ) 한국질량분석학회 2017 Mass spectrometry letters Vol.8 No.2

Isothiazolinone derivatives are widely used in consumer products as disinfectants or preservatives, but there are growing concerns about their impact on human health. Therefore, rapid screening of these biocides is very important for proper control and regulation of potentially hazardous substances. To this end, low-temperature plasma (LTP) ionization mass spec-trometry (MS) was investigated to demonstrate its potential for direct and selective analysis of isothiazolinones from sprayed aerosol samples. Benzisothiazolinone (BIT) was clearly identified from a commercial fabric deodorant using LTP ionization MS and MS/MS. LTP allowed selective ionization of BIT directly from the simply sprayed aerosol sample and illustrated its poten-tial for fast screening without sample pre-treatments. Selective nature of LTP ionization, on the other hands, implicates use of LTP ionization MS as a general screening method for specific groups of hazardous chemicals in commercial products.