Extended Data Figure 6: Central sections of the 3D full-pattern diffraction volume.

a–c, Bragg intensities in planes normal to the three orthogonal reciprocal-space axes, q_z, q_y and q_x, respectively, which were arbitrarily chosen to be parallel to the c*, b* and a* axes of the PSII crystal. The 4.5-Å extent of the Bragg peaks is indicated by the red circle. d–f, Full-pattern diffraction intensities in central sections normal to the same three orthogonal axes as in a–c, respectively, obtained from that 2,848 strongest snapshot diffraction patterns. g–i, Continuous diffraction intensities calculated for a single PSII dimer using the model refined from the 4.5-Å Bragg data, for the same set of orthogonal planes as in a–c, respectively. The intensities were calculated from the incoherent sum of the squared modulus of the 3D molecular transform of a single (uncrystallized) PSII dimer in each of the four orientations of the 222 point group. All panels are plotted on the same scale, with the experimental data (d–f) extending to q = 0.33 Å⁻¹ at the centre edge. The agreement between each of d–f with the corresponding panel g–i is further evidence that the rigid structural unit is the PSII dimer.