Maximum entropy EM tomography: demonstration of improved resolution with adenovirus
EMT is a method for three-dimensional (3-D) reconstruction of single objects from electron microscope pictures in a tilt series. The EMT method is general and can be applied to any transparent object, and is not restricted to symmetrical or regularly arranged objects, nor to objects with preferred orientations on a support grid. In its present shape, the EMT method allows reproducible 3-D reconstructions of molecular objects with a resolution in the range of 5 nm. Currently, the EMT method covers the intermediate resolution range where there is no other physical technique available to analyze single molecular complexes.The recent availability of techniques for high quality automatic data collection from vitrified specimens at low dose promises an improvement of the reproducible resolution as well as considerable expansion of the number of users of the EMT technique. A serious drawback of EMT, however, has been the notoriously low quality of single-object 3-D reconstructions when compared to symmetrized reconstructions.