Superoxide sensitivity of the Escherichia coli aconitase.

摘要: Mutants of Escherichia coli lacking superoxide dismutase (SOD) activity were used to explore the sensitivity aconitase toward O2 and O2-. The in SOD-free extracts was rapidly lost under aerobic conditions exogenous SOD afforded a concentration-dependent protection. rate inactivating reaction between O2- estimated be order 10(9) M-1 s-1. competitive inhibitors fluorocitrate tricarballylate provided some protection, at saturating concentrations, they decreased by 100- 10-fold, respectively. Aconitase markedly less sensitive than it Aerobic growth on succinate involves greater dependence upon does glucose and, as expected, deleterious consequences deficiency more pronounced glucose. Moreover, lower aerobically grown mutants, parental strain. We suppose that inactivation oxidative attack prosthetic iron-sulfur cluster. extreme suggests its will an early event stress imposed hyperoxia, ultraviolet irradiation or redox-cycling agents, such viologens quinones.