Micro‐Crystallography Developments at GM/CA‐CAT at the APS

Recently, several important structures have been solved using micro‐crystallographic techniques that previously could not have been solved with conventional crystallography. At GM/CA‐CAT we continue to develop micro‐crystallographic capabilities for difficult problems such as small crystals of large macromolecular complexes or membrane proteins grown in the lipidic cubic phase. This paper will describe three major upgrades to our arsenal of tools, “mini‐beam” collimators, active beamstop, and an improved goniostat. Our “mini‐beam” collimators have evolved to a new triple‐collimator fabricated from molybdenum as a uni‐body. This has significantly improved the robustness, ease of initial alignment, and reduction of background. More recently, two prototypes of a quad‐collimator have been developed and fabricated to provide a selection of mini‐beams of 5, 10, 20 μm and a 300 μm scatter‐guard on a single body. The smaller beams and samples have increased the demand on the tolerances of our goniostat. To meet t...