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![[Figure 3]](qu5005fig3mag.jpg)
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Figure 3
Global versus specific radiation damage. Top row, left: a single crystal of a hypothetical protein is depicted with three specific radiation damage-sensitive groups: a disulfide bridge, an oxidized metal cation and a residue with a carboxylate group located in the active site (AS). Top row, right: the crystal is affected by global damage (blue dots) with various effects, in particular that of perturbating crystal contacts upon X-ray-induced protein movement within the cell (black arrows), leading to a loss of diffraction resolution, an increase in mosaicity and increased B factors. Specific damage (red dots) develops on the aforementioned radiosensitive chemical groups, leading to disulfide-bridge reduction (rupture), metal-cation reduction and residue decarboxylation. Middle row: illustration of the damage dose scale at cryogenic temperature. Global damage builds up slowly, while specific damage builds up relatively rapidly, so as to be visible at low doses in Fourier difference maps calculated between successive data sets 1 and n, Fobs(n) − Fobs(1), and at high doses in Fcalc − Fobs and 2Fcalc − Fobs maps. The maximum acceptable dose is typically that of the Garman limit (30 MGy). Bottom row: illustration of the damage dose scale at room temperature: both types of damage build up on a similar dose scale, complicating the precise identification of specific damage. The maximum acceptable dose for a single crystal is a few hundreds of kilograys, i.e. typically one hundredth of the Garman limit. |
![[Figure 3]](qu5005fig3.jpg)
 | STRUCTURAL BIOLOGY |
ISSN: 2059-7983
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