Topoisomerase II-Catalyzed ATP Hydrolysis as Monitored by Thin-Layer Chromatography

Although type I topoisomerases do not require a high-energy cofactor, type II topoisomerases require ATP in order to carry out their essential catalytic functions (1 –4 ). ATP binding is necessary to close the protein clamp (5 ,6 ) and trigger DNA strand passage (7 ,8 ), whereas hydrolysis is necessary for topoisomerase II recycling (7 ,8 ). Beyond the the critical roles played by ATP in the catalytic cycle of the enzyme, interactions between type II topoisomerases and ATP are also affected by compounds with antimicrobial and anticancer properties. For example, coumarin-based antimicrobials block DNA gyrase function specifically by inhibiting ATP hydrolysis (7 –11 ). In addition, several anticancer drugs that act by enhancing topoisomerase II-mediated DNA cleavage also impair interactions between the enzyme and ATP (12 ).