Lumazine Synthase was expressed in E.coli and purified by immobilised metal affinity chromatography. Particles were frozen on C-flat R1.2/1.3 grids. Imaging was performed at 200 kX magnification on a JEOL CryoARM 300 equipped with a Direct Electron DE64 detector. Energy filtered images were collected with a slit-width of 20eV using JADAS. A single image was recorded per hole using electron counting with two times binning.