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Figure 1
Bragg diffraction at sub-nanometer resolution from soluble protein 2-D crystals. (a) Background-subtracted diffraction pattern for 2-D crystals of streptavidin. Blue circles signify resolution rings at 30.0, 15.0 and 7.5 Å (inner to outer). The zoomed-in red circles indicate Bragg spots with highest resolution at 8.0 Å, (h, k) = (−10, 2) and (2, 10), while the black box zoom highlights two lattice spots at intermediate resolution. The diffraction patterns were acquired with a sample-to-detector distance of 560 mm and a photon energy of 8448 eV. Owing to C222 symmetry (h + k = 2n), the innermost reflections are (0, 2), (1, 1) and (2, 0). (b) 2-D electron density projection map (2 × 2 unit cells) from coupling the observed integrated peak intensities with the corresponding calculated phases from the known crystal structure. (c) Ribbon diagram of a 2 × 2 unit cell of streptavidin created using the known crystal structure, symmetry and unit cell for comparison with (b). The scale bar is equivalent for panels (b) and (c).

Volume 1| Part 2| February 2014| Pages 95-100
ISSN: 2052-2525