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Crystal structure of the cyanide‐inhibited Xenopus laevis Cu,Zn superoxide dismutase at 98 K
Author(s) -
Carugo Kristina Djinovic,
Battistoni Andrea,
Carrì Maria Teresa,
Polticelli Fabio,
Desideri Alessandro,
Rotilio Giuseppe,
Coda Alessandro,
Bolognesi Martino
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)00651-2
Subject(s) - xenopus , superoxide dismutase , cyanide , chemistry , crystal (programming language) , crystallography , biochemistry , inorganic chemistry , enzyme , gene , computer science , programming language
The crystal structure of cyanide‐inhibited X. laevis Cu,Zn superoxide dismutase has been studied and refined based on diffraction data collected at 98 K. The final R ‐factor for the 27,299 reflections in the 10.0‐1.7 Å resolution range is 0.170. The cyanide anion, which is a competitive inhibitor expected to mimic the superoxide binding mode, binds directly to the active site copper atom, replacing the coordinated water molecule. Moreover, the anion establishes a strong electrostatic interaction with the guanidinium group of the conserved active site residue Arg 141 . The coordination sphere of Cu 2+ is partly altered with respect to the uninhibited enzyme: a displacement of 0.41 Å in subunit A, and 0.27 Å in subunit B of the dimeric enzyme is observed for the Cu 2+ ions. Only two ligands in the Cu 2+ coordination sphere (His 46 and His 118 ) are significantly affected by cyanide binding, whereas virtually no rearrangement of the Zn 2+ ligands is reported.