Title page for ETD etd-11012008-063433


Type of Document Master's Thesis
Author Kittiponkul, Vipavadee
URN etd-11012008-063433
Title Effect of oxidative stress on Escherichia coli sodA-sodB- :protection by the mimic of superoxide dismutase, Mn(III)-salophen
Degree Master of Science
Department Biochemistry
Advisory Committee
Advisor Name Title
Gregory, Eugene M. Committee Chair
Bevan, David R. Committee Member
Hess, John L. Committee Member
Misra, Hara P. Committee Member
Keywords
  • superoxide dismutase
  • Mn(III)-salophen
  • Escherichia coli
  • paraquat
Date of Defense 1996-12-19
Availability restricted
Abstract

The effect of Mn(III)-salophen, a superoxide scavenger, against oxidative stress was evaluated in Escherichia coli sodA- sodB-. Oxidative stress was imposed by exposure of the cells to paraquat or hyperoxia. Cells were grown in LB medium overnight, washed and resuspended in the indicated glucose/salts medium supplemented with casamino acids. The effect of Mn(III)-salophen in the oxidative stress model in vivo was measured in terms of the cell growth. Mn(III)-salophen ( 60 nM) completely protected E. coliJI132sodA- sodB-against 1.0 μM paraquat. Equivalent amounts of Mn(III) acetate, a Mn(III)-salophen component, also protected against paraquat toxicity in aerobic E. coli JI132sodA- sodB-. Fe(III)-salophen which has no superoxide scavenging activity, did not protect the cells against paraquat toxicity. The protective effect of Mn(III)-salophen against the paraquat toxicity was proposed to come from the intracellular superoxide scavenging activity of either the complex itself, its component Mn(III), or both, but not by inhibiting the uptake of paraquat. The protective effect of Mn(III)-salophen and Mn(III) in the glucose/salts medium containing casamino acids was also observed in E. coli sodA- sodB- in 100% and 50% oxygen. Hyperoxia increases intracellular levels of superoxide radicals that are intercepted by Mn(III)salophen and Mn(III).

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