사람 태반조직 DNA topoisomerase I에 관한 연구 = Studies on DNA Topoisomerase I from Human Term Placenta

다국어 초록 (Multilingual Abstract)

DNA topoisomerase I has been purified from human term placenta approximately 520-folds with a 10% yield. The enzyme shows a broad pH optimum from pH 6 to 9 and is heat-labile, being completely inactivated by heat treatment at 50℃ for 5 minutes. The enzyme is activated by K^+ and Na^+ approximately 20 and 8-folds respectively. Magnesium ion(Mg^2+) is the most potent activator, the activity being 20 and 40-folds activated at 2mM and 10mM respectively. But copper ion(Cu^2-) is a potent inhibitor. In the presence of Mg^2+ and K^+, the enzyme is inhibited by physiologic concentration of ATP and GTP. Inhibitory mechanism of ATP is considered to be an inhibition of readoptation of an active enzyme conformation and that of GTP is an inhibition of the prior step of DNA rejoining. The molecular weight is about 68,000. Camptothecin and 10-hydroxycampto-thecin inhibit this enzyme, and the inhibitory action of 10-hydroxycamptothecin is potentiated in the presence of Mg^2+ and K^+ DNA fragmentation by 10-hydroxycamptothecin is more prominent than that by camptothecin in DNA cleavage assay. Heparin and Cu^2+ inhibit the prior step of DNA rejoining by this enzyme.
From the above results, the inhibitory action mechanism of ATP, GTP, heparin, Cu^2+ and the possible role of Mg^2+ and K^2+ for potentiating the inhibitory action of 10-hydroxycamptothecin, and the development of the anticancer drug against DNA topoisomerase I as a target enzyme are discussed.

목차 (Table of Contents)

• 목차
• I. 서론 = 1
• II. 실험재료 및 방법 = 1
• III. 실험성적 = 2
• IV. 고찰 = 9
• V. 결론 = 10
• 참고문헌 = 11
• Abstract = 14