EXTRACELLULAR-SUPEROXIDE DISMUTASE FROM STREPTOCOCCUS-PYOGENES TYPE-12 STRAIN IS MANGANESE-DEPENDENT

Highly purified extracellular superoxide dismutase was obtained from S treptococcus pyogenes strain 12714 (type 12) by adsorption of culture supernatant on phenyl-Sepharose following preparative isoelectric focu sing of eluates and a final gel filtration purification on Superdex 20 0. The purified superoxide dismutase of S. pyogenes was found to be a homodimer. The monomeric protein had a molecular mass of 22 442 Da and an isoelectric point of 4.0. The enzymatic activity was strongly mang anese-dependent. The N-terminal sequence of the purified mature protei n was AIILPELPYAYDALEPQFDA and corresponded to the first amino acids f ollowing the methionine initiation codon with no evidence of a leader sequence for the mature protein. The DNA sequence of the superoxide di smutase gene of strain 12714 was found to be almost identical to the c orresponding sequences reported in the gene bank data from other S. py ogenes serotypes and showed strong homology to superoxide dismutases f rom other Gram-positive bacteria. (C) 1998 Federation of European Micr obiological Societies. Published by Elsevier Science B.V.