Crystal Structures of Actinomycin D and Actinomycin Z3

Untwinned single crystals of the actinomycins D and Z₃ that diffracted to atomic resolution could be obtained for the first time. Low-temperature data collection and a new ab initio method for solving the structures led to precise crystal structures which showed, for example, that the unit cell of actinomycin D contains three molecules, two of which are present in the form of a hydrogen-bridged dimer related by a pseudo-twofold axis (see picture).