title: Structure of phosphate-free ribonuclease A refined at 1.26 A.
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.
authors.affiliation: Center for Chemical Physics, National Bureau of Standards, Gaithersburg, Maryland 20899.
authors.forename: A
authors.initials: A
authors.lastname: Wlodawer
authors.forename: L A
authors.initials: LA
authors.lastname: Svensson
authors.forename: L
authors.initials: L
authors.lastname: Sjölin
authors.forename: G L
authors.initials: GL
authors.lastname: Gilliland
mesh_terms: D001665:Binding Sites; D008958:Models, Molecular; D010710:Phosphates / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D012259:Ribonuclease, Pancreatic / Q000378:metabolism; D014961:X-Ray Diffraction
chemical_list: D010710:Phosphates; D012259:Ribonuclease, Pancreatic