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Welcome to BIOISIS ... the resource for macromolecular SAXS.
Experiment of the Month
Modeling of SAM-1 Riboswitch (apo state)
Low_res_thumbnail SAM-1 riboswitch binds a small metabolite (SAM). Crystal structures of bound and unbound states demonstrate nearly identical structures unlike in solution where SAXS data showed two distinct states of the riboswitch. The riboswitch appears to occupy a single bound state in the presence of SAM identical to the crystal structure whereas in the absence of SAM, the riboswitch appears to occupy many conformational states. Based on the X-ray crystal structure, SAXS data in the absence of SAM-1 was used as a modeling constraint in torsion angle molecular dynamic simulations. Results demonstrate a scissoring of the riboswitch for opening the metabolite binding site.
    

Recent Posts

CHARACTERIZING FLEXIBLE AND INSTRINSICALLY UNSTRUCTURED BIOLOGICAL MACROMOLECULES BY SAS USING THE POROD-DEBYE LAW  

August Issue of Biopolymers is a special issue dedicated to SAXS.
SASTBX  

New SAS analysis software is available called SASTBX. SASTBX provides a novel parameterization of shape using Zernicke polynomials. A databases of prior shapes parameterized using the Zernicke coefficients can be quickly searched with experimental SAXS data within seconds to provide an initial shape estimate. Further refinement of the shape can be achieved. SASTBX is also developing a refinement procedure using a starting atomistic model.
FIXED ENSEMBLE UPLOADING  

BioIsis uploading mechanism was fixed allowing multiple PDBs for ensemble modeling.
2-DAY SAXS WORKSHOP AT VANDERBILT UNIVERSITY  

Vanderbilt University in Nashville, TN, hosted a two-day workshop on Biomolecular SAXS with attendees from St. Jude Children’s Research Hospital on January 21 and 22, 2011. The workshop covered four sections: 1) SAXS Theory, 2) hands-on practical, 3) Techniques for preparing and assessing sample quality, and 4) SAXS based structural modeling.