Structure of phosphate-free ribonuclease A refined at 1.26 A |
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Authors: | A Wlodawer L A Svensson L Sj?lin G L Gilliland |
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Affiliation: | Center for Chemical Physics, National Bureau of Standards, Gaithersburg, Maryland 20899. |
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Abstract: | The structure of phosphate-free bovine ribonuclease A has been refined at 1.26-A resolution by a restrained least-squares procedure to a final R factor of 0.15. X-ray diffraction data were collected with an electronic position-sensitive detector. The final model consists of all atoms in the polypeptide chain including hydrogens, 188 water sites with full or partial occupancy, and a single molecule of 2-methyl-2-propanol. Thirteen side chains were modeled with two alternate conformations. Major changes to the active site include the addition of two waters in the phosphate-binding pocket, disordering of Gln-11, and tilting of the imidazole ring of His-119. The structure of the protein and of the associated solvent was extensively compared with three other high-resolution, refined structures of this enzyme. |
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