3D reconstructions of the 70S ribosome (a), 20S proteasome (b), apo-ferritin (c), ACE2 (d) and streptavidin (e) with atomic resolutions of 2.7, 2.0, 2.1, 3.3 and 1.9 A, respectively (top). The views from the outside (left) and middle sections (right) of 20S proteasome and apo-ferritin have been combined to reveal structure credibility. Zoomed regions of the five macromolecule structures show well-defined densities of side chains, carbonyl bonds and benzene rings (bottom).
