 | Acta Crystallographica Section D Acta Crystallographica Section D BIOLOGICAL CRYSTALLOGRAPHY |
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![[Figure 6]](gx5088fig6mag.jpg)
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Figure 6
Analysis of SeMet incorporation in two proteins expressed in mammalian cells. (a) and (c) correspond to one sample and (b) and (d) to the second. (a) and (b) The two constructs were crystallized and Se K-edge fluorescence scans performed at ESRF beamline BM14 demonstrate Se incorporation. (c) Mass-spectrometric analysis of the peptides obtained by trypsin digestion of the first sample in its native and SeMet-labelled states. The observed pattern is essentially identical apart from one peptide (single star) that is shifted in the SeMet-labelled sample (double star) by a mass corresponding to one sulfur-to-selenium substitution. Two other peptides containing Met residues in this sample could not be detected. However, labelling of these Met residues was subsequently confirmed by crystallographic data processing. (d) Mass-spectrometric analysis of the second protein sample, undigested, containing two Met residues, reveals a peak shift corresponding to teh incorporation of two Se atoms (see double-star versus single-star labels). The data indicate that approximately 60% of the protein sample was labelled. |
![[Figure 6]](gx5088fig6.jpg)
| BIOLOGICAL CRYSTALLOGRAPHY |
ISSN: 1399-0047
