Preparation and Inhibitor Studies of Recombinant Human TopoisomeraseⅡα

• Main Author: 廖欽志
• Other Authors: Tzong-Hsiung Hseu
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/42283608854347880925

碩士 === 國立清華大學 === 生物技術研究所 === 88 === Abstract Topoisomerases are ubiquitous enzymes which can modulate every physiological function of the genome by alter the topological relationship within the double helix, that are required for replication, transcription, and recombination and play critical roles in chromosome structure, condensation/decondensation, and segregation. Beyond their essential cellular functions, topoisomerase Ⅱ are the targets for a number of clinically important drugs. By using an inducible plasmid to overexpression human topoisomerase Ⅱα, we have purified large amount of the enzyme as the target for inhibitor screening. The two plants: Hedyotis diffusa Willd and Curcuma zedoaria Roscoe used in Chinese folk medicine for anti-tumor have been tested in relaxation assay. The result shows the ethyl acetate extract from the two plants by solid phase extraction have the ability to inhibit human topoisomerase Ⅱα in vitro, and Hedytis diffusa is better than the other. In DNA and inhibitor interaction: the result shows the two inhibitors cannot integrate into DNA and neither apparent mobility shift nor interfere double helix separation; but we also discover Curcuma zedoaria can cause the condensation of DNA, but the influence is not a cause of inhibition. By increasing the concentration of substrate 3~5 times, they still cannot change the inhibition even in minimums inhibition concentration, the result shows it is a non-compete inhibition. In cleavage assay the result also shows inhibitors interfere the catalytic site of the enzyme belong to cleavage-complex forming antagonist.