Determination of the X-ray structure of the snake venom protein omwaprin by total chemical synthesis and racemic protein crystallography

Authors

  • James R. Banigan,

    1. Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago. Illinois
    2. Department of Chemistry, The University of Chicago, Chicago. Illinois
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  • Kalyaneswar Mandal,

    1. Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago. Illinois
    2. Department of Chemistry, The University of Chicago, Chicago. Illinois
    3. Institute for Biophysical Dynamics, The University of Chicago, Chicago. Illinois
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  • Michael R. Sawaya,

    1. Molecular Biology Institute, University of California, Los Angeles, California
    2. Department of Chemistry and Biochemistry, University of California Los Angeles, California
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  • Vilasak Thammavongsa,

    1. Department of Microbiology, The University of Chicago, Chicago. Illinois
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  • Antoni P. A. Hendrickx,

    1. Department of Microbiology, The University of Chicago, Chicago. Illinois
    2. Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, The Netherlands
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  • Olaf Schneewind,

    1. Department of Microbiology, The University of Chicago, Chicago. Illinois
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  • Todd O. Yeates,

    1. Molecular Biology Institute, University of California, Los Angeles, California
    2. Department of Chemistry and Biochemistry, University of California Los Angeles, California
    3. University of California Los Angeles-United States Department of Energy Institute for Genomics and Proteomics
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  • Stephen B. H. Kent

    Corresponding author
    1. Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago. Illinois
    2. Department of Chemistry, The University of Chicago, Chicago. Illinois
    3. Institute for Biophysical Dynamics, The University of Chicago, Chicago. Illinois
    • GCIS #W204, 929 East 57th Street, Chicago, IL 60637

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Abstract

The 50-residue snake venom protein L-omwaprin and its enantiomer D-omwaprin were prepared by total chemical synthesis. Radial diffusion assays were performed against Bacillus megaterium and Bacillus anthracis; both L- and D-omwaprin showed antibacterial activity against B. megaterium. The native protein enantiomer, made of L-amino acids, failed to crystallize readily. However, when a racemic mixture containing equal amounts of L- and D-omwaprin was used, diffraction quality crystals were obtained. The racemic protein sample crystallized in the centrosymmetric space group P21/c and its structure was determined at atomic resolution (1.33 Å) by a combination of Patterson and direct methods based on the strong scattering from the sulfur atoms in the eight cysteine residues per protein. Racemic crystallography once again proved to be a valuable method for obtaining crystals of recalcitrant proteins and for determining high-resolution X-ray structures by direct methods.

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