New models of superoxide reductase: Reactivity with alkylperoxides

INOR 104

Frances Namuswe, frances@jhu.edu, Gary D. Kasper, Yunbo Jiang, Divya Krishnamurthy, divya@jhu.edu, and David P. Goldberg. Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218
Anaerobic bacteria rely on superoxide reductase enzymes (SORs) to convert O2- to H2O2 by a one-electron reduction mechanism. The reduced active site, SORred, is comprised of a (His4Cys)FeII center. Although the structure of the active site has been elucidated, several questions regarding the mechanism remain unanswered including 1) what is the importance of thiolate ligation? and 2) what are the reaction intermediates involved—are there Fe(III)-(hydro)peroxo intermediates along the catalytic pathway? We have synthesized a model of SORred, [([15]aneN4)FeII(SPh)]BF4, and have shown that it reacts with alkylperoxides at low temperature to produce novel low-spin Fe(III)-OOR species with weak Fe-O bonds. To determine the effect of the thiolate donor, we have prepared three new complexes [([15]aneN4)FeII(SPhX)]+A-; (X = Cl, A = BF4 (1); X = NO2, A = BF4 (2); and X = NO2, A = SPhNO2 (3)) where the electronic properties of the ArS– donor have been varied. The effect of the thiolate donor on the structure, redox potentials and reactivity of these complexes will be described.
 

Inorganic Modeling of Biological Systems
1:30 PM-5:10 PM, Sunday, August 19, 2007 BCEC -- 208, Oral

Division of Inorganic Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007