“Binding of the … analog inhibitor 2'-deoxycoformycin was rendered 9.8 kcal/… by removal of substituent ribose , 9.7 kcal/mol less favorable by inversion of the 8-hydroxyl substituent of the diazepine … 10.0 kcal/mol less favorable by removal of atoms 4-6 of the diazepine ring.”