DNA-protein covalent complexes detection as the means for the assessment of the DNA damage induced by topoisomerase poisons.

Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Biochemical Sciences Candidate: Aneta Karešová Supervisor: PharmDr. Anna Jirkovská, PhD. Title of diploma thesis: DNA-protein covalent complexes detection as the means for the assessment of the DNA damage induced by topoisomerase poisons. Topoisomerase II is essential cellular enzyme, which modifies the secondary structure of DNA. By introducing a temporary double strand break to DNA it relieves a structural tension raised during transcription and translation. Absolutely indispensable is the role of topoisomerase II in the separation of sister chromatids synthesized in the S-phase of the cell cycle. The mechanism of DNA cleavage involves a covalent bond formed between active site tyrosine and 5' phosphate on both of the DNA strands and through the formed break the other strand or the other DNA molecule can pass. After that, the DNA strands are rejoined and topoisomerase II is detached. The indispensability of topoisomerase II mainly for proliferating cells makes it a great target for the antineoplastic drugs and the molecules belonging to the class of topoisomerase II inhibitors (etoposide, anthracyclines) are amongst the most useful anticancer drugs in the clinical practice. These clinically used "topoisomerase..