title: Three-dimensional structure of Gln25-ribonuclease T1 at 1.84-A resolution: structural variations at the base recognition and catalytic sites.
abstract: The structure of the Gln25 variant of ribonuclease T1 (RNase T1) crystallized at pH 7 and at high ionic strength has been solved by molecular replacement using the coordinates of the Lys25-RNase T1/2'-guanylic acid (2'GMP) complex at pH 5 [Arni et al. (1988) J. Biol. Chem. 263, 15358-15368] and refined by energy minimization and stereochemically restrained least-squares minimization to a crystallographic R-factor of 14.4% at 1.84-A resolution. The asymmetric unit contains three molecules, and the final model consists of 2302 protein atoms, 3 sulfates (at the catalytic sites), and 179 solvent water molecules. The estimated root mean square (rms) error in the coordinates is 0.15 A, and the rms deviation from ideality is 0.018 A for bond lengths and 1.8 degrees for bond angles. Significant differences are observed between the three molecules in the asymmetric unit at the base recognition and catalytic sites.
authors.affiliation: European Molecular Biology Laboratory, Heidelberg, Germany.
authors.forename: R K
authors.initials: RK
authors.lastname: Arni
authors.forename: G P
authors.initials: GP
authors.lastname: Pal
authors.forename: K G
authors.initials: KG
authors.lastname: Ravichandran
authors.forename: A
authors.initials: A
authors.lastname: Tulinsky
authors.forename: F G
authors.initials: FG
authors.lastname: Walz
authors.forename: P
authors.initials: P
authors.lastname: Metcalf
mesh_terms: D000595:Amino Acid Sequence; D001236:Aspergillus oryzae / Q000201:enzymology; D001665:Binding Sites; D002384:Catalysis; D005973:Glutamine / Q000737:chemistry*; D006150:Guanine Nucleotides / Q000737:chemistry*; D011487:Protein Conformation; D006163:Ribonuclease T1 / Q000737:chemistry*; D013329:Structure-Activity Relationship; D013816:Thermodynamics; D014961:X-Ray Diffraction
chemical_list: D006150:Guanine Nucleotides; D005973:Glutamine; D006163:Ribonuclease T1