NECAT Beamline

The Northeastern Collaborative Access Team (NE-CAT) facility at the Advanced Photon Source at Argonne National Laboratory is managed by Cornell University and consists of seven member institutions:

  • Columbia University
  • Cornell University
  • Harvard University
  • Memorial Sloan-Kettering Cancer Center
  • Massachusetts Institute of Technology
  • Rockefeller University
  • Yale University.

    • Primary funding for this project comes from the National Center for Research Resources (NCRR), a division of the National Institutes of Health (NIH). Additional financial support for NE-CAT comes from the member institutions.

    Status of NE-CAT Sector 24 Activities

     

    July 2007  

     

    After APS’ month long shut down in May, user activities on both of NE-CAT‘s insertion device beam lines resumed in earnest upon resumption of accelerator operations in June. The operational 24-ID-C beam line was fully booked during June and July with NE-CAT institutional users and APS General Users. The beam line continued to operate with a high-degree of reliability and all users reported successful experiments.

    During the May shutdown, additional enhancements were made to the MD2 micro-diffractometer installed on the 24-ID-E beam line. Upon resumption of APS operations in June, early experiments were devoted to reducing the scattering background to an absolute minimum before the micro-diffractometer would be turned over to the users. The major source of background was established to originate from the MD2 primary aperture. ACCEL/Metal has informed us that a scattering guard was mistakenly omitted in our installation. Before this could be corrected by the vendors in October, this source of scattering was effectively removed by inserting an additional pin-hole lead absorber just upstream of the aperture. Having achieved an acceptably low level of scattering background, experiments began to access the feasibility of a number of proposed projects with NE-CAT’s core collaborators. Here we will describe several of these exploratory experiments.

    The first experiments used several peptide fibril samples from David Eisenberg’s laboratory at UCLA as part of a collaborative activity, as illustrated below.

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    Good diffraction patterns were obtained from two fibril samples with dimensions of 3x3x50 microns using beam sizes of 20 and 5 microns. These exploratory experiments were so successful that David Eisenberg’s group has now scheduled several days of MD2 beam time to conduct their experiments in earnest.

    The second set of exploratory collaborative experiments were directed to extremely radiation sensitive crystals from Steve Harrison’s group at Children’s Hospital-Boston and Harvard Medical School, generally of size 5x20x100 microns. It was demonstrated that good data frames could be obtained by moving from one exposure area to another on the same crystal when radiation damage began to affect data quality. In all, four different areas were irradiated using a 20 micron beam as shown on the figure below.

    This exploratory experiment clearly showed the feasibility of obtaining high-quality data using multiple exposures on the same radiation sensitive crystal.

    A third exploratory experiment, conducted in collaboration with James Berger’s group from the University of California-Berkeley was designed to ascertain the feasibility of obtaining data sets from very small crystals grown and still remaining in micro-fluidic chips. Figure “a” below shows thaumatrin crystals in a micro-fluidic chip mounted on the MD2 micro-diffractometer. As can be seen in Figure “b”, this exploratory experiment was very successful, yielding a very good, clean, diffraction image.

    “a”
    “b”

     

    A fourth collaborative experiment conducted with Robert Thorne’s group at Cornell examined the effectiveness of using matrix mounts to collect small crystals and obtain structural data. A matrix mount consisting of 25 micron openings is shown below in Figure “a”. The matrix mount “sieve” was passed through a crystallization solution containing many very small RNA methyl transferase micro-crystals, most less than 5 microns in size. With the matrix sieve, crystals of sizes comparable or larger than the 25 micron sieve openings could efficiently be collected as shown in Figure “b”.

    "a"
    "b"

     

    Five to eight diffraction images were collected from 16 different crystals and scaled together to produce a near complete 3.3 Å data set.

    These first collaborative experiments have clearly demonstrated the power of the new MD2 micro-diffractometer and the new areas of research its usage has opened up. Based on these earliest successes, all the collaborative groups have scheduled time on the 24-ID-E MD2 beam line during the summer APS operational schedule to continue pursuing these experiments.

     

    * The June 2007 Status Report has been combined with the July 2007 Status Report due to illness of the contributor during this period.

     

     

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