Figure 1.

Principles of single-molecule measurement using DXT. (A) The relative positions of the gold nanocrystal-labeled peptide/MHC complex on the basal plate, the radiation beam, and the image plane are shown. Diffraction spots from single nanocrystals were video-recorded at a rate of 36 ms/f and the trace locations were translated into motion in real space. The large black circle on the left is the umbra of the beam stop for the direct x-ray beam. θ, tilting motion; χ, rotational motion. (B) Schematic model for the peptide (with the L56C mutation) and MHC (without mutation) labeled with gold nanocrystals. (C) The θ direction of the Laue pattern movement is assigned to the tilted motion of the peptide/I-A^k complex. The χ direction of the Laue pattern movement is assigned to the rotational motion of the peptide/I-A^k complex. To see this figure in color, go online.