Table 7.13.2.

Electron Microscopy versus X-Ray Crystallography

Variable	EM	Crystallography
Sample size	Relatively low amounts of material needed	Milligram quantities required
Crystals	No need for single crystals	Crystallization constitutes a bottleneck on the way to structure determination
Molecular size	Typically applied to large-size macromolecules or assemblies, (>300 kDa), but the technique has been successfully applied to a 78-kDa DNA nanostructure (Kato et al., 2009)	No intrinsic size limitation (structures up to the MDa size range have been determined); however, large molecules can be difficult to crystallize
Resolution	Typically 10 Å or less; but near-atomic resolution is possible (Zhou, 2008; Liu et al., 2010, Binshtein and Ohi, 2015; Rodriguez et al., 2015), and the number of cryo-EM structures with resolutions of 5 Å and higher is steadily increasing	Near-atomic resolution can be achieved even with very large molecules, permitting detailed insights into recognition and mechanistic aspects