 | Acta Crystallographica Section F Acta Crystallographica Section F STRUCTURAL BIOLOGY COMMUNICATIONS |
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![[Figure 1]](no5183fig1mag.jpg)
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Figure 1
The modification of Cys528 by 2-mercaptoethanol (BME). 2mFo − DFc (contoured at 1.0σ in blue) and mFo − DFc (contoured at 3.0σ in green and −3.0σ in red) difference electron-density maps around Cys528 generated after model refinement with unmodified cysteine in (a) and (b) and after refinement of the covalently modified Cys528–BME conjugate model in (c). Nonmodified cysteine demonstrates an excess electron-density map representing a pronounced positive peak in the mFo − DFc map (a). The S atom of the modeled BME occupies the center of the excess electron-density map peak observed close to Cys528 (b). (c) Crystallographic refinement of the atomic model containing the Cys528–MBE conjugate. Neither positive nor negative peaks in the mFo − DFc map could be observed at contour levels of 3.0σ and −3.0σ, respectively. The methyl hydroxy moiety (indicated by an arrow) was not visible in the electron-density map due to its flexibility (rotational freedom). (d) A polder OMIT map of the Cys528–BME conjugate (contoured at 2.2σ in blue) confirms that Cys528 modification by BME explains the excess electron-density peak. |
![[Figure 1]](no5183fig1.jpg)
| STRUCTURAL BIOLOGY COMMUNICATIONS |
ISSN: 2053-230X
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