Superoxide dismutases containing manganese or iron can be resolved by exposure to low pH in the presence of guanidinium chloride. Apoenzymes so produced are inactive and are reactivated only by the metal characteristic of the native enzymes. In crude extracts of procaryotes, which may contain the iron enzymes or the manganese enzyme or both together, one can, by resolution followed by treatment with Fe(II) or Mn(II), identify and distinguish these enzymes. This method was validated with extracts of Escherichia coli, known to contain both types of enzymes, and was then used to demonstrate the presence of an iron superoxide dismutase in Alcaligenes faecalis and of manganese superoxide dismutases in Streptococcus sanguis, S. lactis, Bacillus megaterium, and Acholeplasma laidlawii. The A. laidlawii enzyme was found to have a molecular weight of ~41,000.
ASJC Scopus subject areas
- Molecular Biology