title: X-ray microdiffraction and conventional diffraction from frozen-hydrated biological specimens.
abstract: A system for recording microdiffraction patterns from micrometer-sized quick-frozen hydrated biological specimens at the high-flux beamline BL40XU of SPring-8 is described. The optics consists of a pair of pinholes drilled into tantalum substratum, with a defining aperture of diameter 2 microm. The frozen specimens are placed in an in-vacuum cryochamber mounted on a three-axis goniometer, where the specimens are stably held at a liquid-nitrogen temperature ( approximately 74 K). A beam size of 1.5 microm (full width at half-maximum) is attained at the sample position. By using this system, diffraction patterns have been recorded from an isolated single myofibril (diameter approximately 3 microm) of an insect flight muscle in an area equivalent to a single sarcomere (length approximately 3 microm). The technique is potentially applicable to other micrometer-sized hydrated biological specimens, which are more susceptible to radiation damage than dry synthetic polymers or biopolymers. The quick-freezing of biological specimens has also been proven useful in reducing the specimen volume in the beam in conventional diffraction recordings.
authors.affiliation: Research and Utilization Division, SPring-8, Japan Synchrotron Radiation Research Institute, Hyogo 679-5198, Japan. iwamoto@spring8.or.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Iwamoto
authors.forename: Katsuaki
authors.initials: K
authors.lastname: Inoue
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Fujisawa
authors.forename: Naoto
authors.initials: N
authors.lastname: Yagi
mesh_terms: D000818:Animals; D001516:Bees / Q000737:chemistry / Q000648:ultrastructure; D002478:Cells, Cultured; D015925:Cryopreservation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D018482:Muscle, Skeletal / Q000737:chemistry / Q000648:ultrastructure; D009210:Myofibrils / Q000737:chemistry* / Q000648:ultrastructure*; D013048:Specimen Handling / Q000295:instrumentation* / Q000379:methods*; D013052:Spectrometry, X-Ray Emission / Q000295:instrumentation* / Q000706:statistics & numerical data; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction / Q000295:instrumentation* / Q000379:methods*
chemical_list: D014867:Water