INOR 760 |
| Superoxide dismutases (SODs) are enzymes that catalyze the conversion of superoxide to oxygen and hydrogen peroxide, and thus play critical roles in mitigating the effects of reactive oxygen species and in respiratory stress. The enzyme that contains nickel at the active site is unique in several ways: it is the only variation of the enzyme (others include MnSOD, FeSOD and CuZnSOD) that utilizes a metal ion that is unable to catalyze the disproportionation of superoxide in the absence of the protein, and it is the only SOD that features cysteine thiolate ligation. Despite these differences, the enzyme has a redox potential for the Ni(II/III) couple of 286(10) mV, similar to that of other SODs. The protein environment clearly plays a critical role in conferring redox activity on the nickel site. We will report the effects on structure and reactivity of mutant NiSODs involving all first coordination sphere ligands, with the exception of a backbone amidate N-donor. In addition, key residues in the second coordination sphere that modulate the interaction between the nickel and the ligands, or between subunits of the hexameric enzyme will be discussed. These studies include the crystal structure of Y9F-NiSOD, which reveals an anion binding site near the active site. |
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Bioinorganic Chemistry: Enzymes and Coenzymes
7:00 PM-10:00 PM, Tuesday, August 21, 2007 BCEC -- Exhibit Hall - B2, Poster
Sci-Mix
Division of Inorganic Chemistry |