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![[Figure 1]](qq5002fig1mag.jpg)
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Figure 1
(a) Percentages of a 13.0 keV incident beam that interact with a 30 µm thick crystal of metallo-β-lactamase (PDB entry 1znb; Concha et al., 1996  ) (i) without and (ii) with Zn. Also shown are the percentages that diffract and are absorbed. (b) X-ray photoelectric scattering cross sections for H, C, N, O, S, Zn and Se for 13.0 keV incident X-ray energy. The areas of the circles are proportional to the cross sections [1.85 × 10−3 (data not shown), 17.7, 35.7, 64.6, 1217, 12 790 and 19 300 barns per atom, respectively; 1 barn = 10−28 m2; after Ravelli et al., 2005]. (c) Primary X-ray interaction processes with the atoms of the crystal and solvent. (i) Elastic (aka Thomson, coherent) scattering. The waves add vectorially to give the diffraction pattern. (ii) Compton (aka incoherent) scattering. The X-ray transfers some energy to an atomic electron and thus has lower energy (higher wavelength) after the interaction. (iii) Photoelectric absorption. The X-ray transfers all its energy to an atomic electron, which is then ejected. The excited atom can then emit a characteristic X-ray or an Auger electron to return to its ground state. Reproduced from Garman (2010). |
![[Figure 1]](qq5002fig1.jpg)
 | STRUCTURAL BIOLOGY |
ISSN: 2059-7983
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