| The transition metal complexes iron diethylenetriaminepentaacetic acid and ferrioxamine B, a tris-hydroxamate siderophore complex, are effective agents against fatality from septic shock in animal models. The mechanism of protection most probably derives from a high affinity of the ferrous forms of the iron complexes for nitric oxide, a suspect agent in the initiation of septic shock. Reduction to the ferrous complex leads to sequestration of NO and protection against sepsis.;Ferrioxamine B is an effective catalyst for the reduction of nitric oxide. This catalysis can be initiated by the electrochemical reduction of the ferric form of the siderophore complex to the Fe(II) form, which reacts quickly with NO. The efficiency of the reduction can be assessed either from catalytic enhancement in cyclic voltammetry or from stopped-flow experiments where the Fe(II) complex is mixed with NO. Under bulk electrolysis conditions, the reaction exhibits multiple turnovers with no apparent degradation of the catalyst. Ferrioxamine B also catalyzes the reduction of NO;The present research indicates a possible new role for siderophore complexes as redox catalysts. The difference in the stabilities of the ferrous and ferric forms of the complex provide an effective driving force for the catalytic reduction of substrate, and the stability of the siderophore complex leads to enhanced stability in the catalysis. These ideas are supported by the cyclic voltammetry of the ferric complex of N, N... |
