Figure 4.

Increasing Mn(II) content in PS II due to radiation damage. (Solid blue line) Mn(II) content in PS II crystals as a function of X-ray irradiation at 13.3 keV (0.933 Å). The irradiation was carried out at 100 K. The conditions are similar to those during XRD data collection. (Dashed blue line) The damage profile for PS II solution samples, which is very similar to that seen for crystals although slightly higher for the same dose. EXAFS spectra of samples shown in Figure 5 are at the levels of damage denoted (on the right) by A–D (0.05, 0.1, 0.3, and 1.4 × 10¹⁰ photons/μm², respectively, at 13.3 keV and 100 K). An average dose of ~3.5 × 10¹⁰ photons/μm² was used for XRD studies. (Dashed green line) Generation of Mn(II), which is considerably greater when the X-ray irradiation is at 6.6 keV (1.89 Å), which is the energy at which the anomalous diffraction measurements for PS II were conducted. (Solid blue line) Mn(II) produced by damage in crystals, which is considerably decreased when the irradiation is conducted at 10 K. The figure is adapted from Yano et al.²³