This structure is the complex of human Topoisomerase IIalpha (hTopoIIalpha) and the compound adenylyl-imidodiphosphate (AMP-PNP or ANP), which has been reported as a competitive inhibitor of ATPase activity of hTopoIIalpha. It binds at the ATP-binding site. Thus, this structure is complexed with two molecules of ANP bound at the two ATP-binding sites. ANP is a good substrate for enzymes hydrolyzing between the alpha- and beta-phosphorus atoms, but is resistant to enzymes cleaving between the beta- and gamma-phosphorus atoms (such as hTopoIIalpha).