Evidence for the formation of disulfide radicals in protein crystals upon X-ray irradiation

Weik, M.; Bergès, J.; Raves, M.L.; Gros, P.; McSweeney, S.; Silman, I.; Sussman, J.L.; Houée-Levin, C.; Ravelli, R.B.G.

doi:10.1107/S0909049502014589

Figure 1
Electron-density maps and models for the three disulfide bonds in TcAChE, viz. Cys402—Cys521, Cys254—Cys265 and Cys67—Cys94, for the first (A) and last (I) of a series of nine data sets collected on a single crystal at 100 K. Electron-density maps are contoured at a level of 1.5σ. During structure refinement, the S atoms were not restrained to form disulfide bonds and their van der Waals radii were set to zero in order to avoid repulsion. The programs MOLSCRIPT (Kraulis, 1991