Corynebacterium glutamicum superoxide dismutase is a manganese-strict non-cambialistic enzyme in vitro

摘要

Superoxide dismutase (SOD) of Corynebacterium glutamicum was purified and characterized. The enzyme had a native molecular weight of about 80kDa, whereas a monomer with molecular weight of 24kDa was found on SDS-PAGE suggesting it to be homotetramer. The native SOD activity stained gel revealed a unique cytosolic enzyme. Supplementing growth media with manganese increased the specific activity significantly, while adding iron did not result in significant difference. No growth perturbation was observed with the supplemented media. In vitro metal removal and replacement studies revealed conservation of about 85% of the specific activity by substitution with manganese, while substitution with copper, iron, nickel or zinc did not restore any significant specific activity. Manganese was identified by atomic absorption spectrometer, while no signals corresponding to fixing other metallic elements were detected. Thus, C. glutamicum SOD could be considered a strict (non-cambialistic) manganese superoxide dismutase (MnSOD).