Complementing crystallography: the role of cryo-electron microscopy in structural biology (original) (raw)

Dramatic improvements in experimental methods and computational techniques have revolutionized three-dimensional image reconstruction from electron micrographs (EM) of vitri®ed samples. Recent results include the ®rst determination of a protein fold (for the core protein of the hepatitis B virus) by non-crystalline imaging techniques. These developments have generated interest within the crystallographic community and have led to a re-evaluation of the technique, particularly amongst those working in the ®eld of virus structure or struggling with the phasing of large macromolecular assemblies. A simple discussion of the techniques of EM image reconstruction and its advantages and problems in terms familiar to crystallographers will hopefully allow an appreciation of the essential complementarity of the two techniques and the practical potentials for phasing applications.