Abstract: The mechanism of action of drugs has been a common interest of people worked in the field of pharmacy, chemistry, biology and medicine. To explore the mechanism of action of a drug, it is important to elucidate the binding mode and interactions between the drug and its receptor. When the X-ray co-crystal structures of the drug and its receptor is available, with the assistance of molecular graphic software, the binding mode and interactions between the drug and its receptor can be visually observed at molecular level, which provides useful information in exposing the mechanism of action of the drug and designing new drugs. Taken nuclear DNA topoisomerase I as an example, this review shows how to familiarize ourselves with the relevant literature,how to understand the related advances,how to collect the structural information of bio-macromolecules from the public library,how to properly use the modeling software and how to correctly analyze the action mechanism of drugs,which are the essential knowledge and arts of the undergraduates,postgraduates,teachers and researchers in pharmacy, chemistry, biology and medicine.

Key words: drug, mechanism, structure, interaction, DNA topoisomerase Ⅰ