Cysteine protease activity of streptococcal pyrogenic exotoxin B

Can J Microbiol. 1994 Nov;40(11):930-6. doi: 10.1139/m94-149.


Streptococcal pyrogenic exotoxin B (SPE B) was purified and its protease and mitogenic activities were investigated. The apparent molecular mass of SPE B purified in the presence of iodoacetic acid was 42 kDa, whereas 29-kDa SPE B was predominant without the reagent. A polyclonal antibody raised against the 29-kDa species reacted with both species, indicating that the 42-kDa species was a precursor of the 29-kDa entity. Both the 42- and 29-kDa species enhanced [3H]thymidine incorporation into human peripheral blood mononuclear cells, whereas neither had any effect on T cell depleted mononuclear cells. The 29-kDa SPE B possessed caseinolytic activity, with an optimal pH of 8, and the activity was specifically suppressed by the antibody. A group of cysteine protease inhibitors, but no serine-, metallo-, or acidic-protease inhibitors, limited the protease activity, whereas dithiothreitol increased the activity. The DNA sequence around a putative active cysteine residue was identical among the speB genes from Streptococcus pyogenes R70, NY-5, and T19. Taken together, these results indicate that SPE B is identical to a cysteine protease, streptopain (EC

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Antibodies, Bacterial
  • Bacterial Proteins*
  • Base Sequence
  • Binding Sites
  • Cells, Cultured
  • Cysteine Endopeptidases / chemistry
  • Cysteine Endopeptidases / immunology
  • Cysteine Endopeptidases / isolation & purification
  • Cysteine Endopeptidases / metabolism*
  • Cysteine Proteinase Inhibitors / pharmacology
  • Dithiothreitol / pharmacology
  • Exotoxins / chemistry
  • Exotoxins / immunology
  • Exotoxins / isolation & purification
  • Exotoxins / metabolism*
  • Genes, Bacterial / genetics
  • Humans
  • Leukocytes, Mononuclear
  • Membrane Proteins*
  • Mitogens / metabolism
  • Molecular Sequence Data
  • Molecular Weight
  • Sequence Analysis, DNA
  • Sequence Homology, Nucleic Acid
  • Species Specificity
  • Streptococcus pyogenes / chemistry*
  • Streptococcus pyogenes / enzymology*


  • Antibodies, Bacterial
  • Bacterial Proteins
  • Cysteine Proteinase Inhibitors
  • Exotoxins
  • Membrane Proteins
  • Mitogens
  • SpeA protein, Streptococcus pyogenes
  • erythrogenic toxin
  • Cysteine Endopeptidases
  • streptopain
  • Dithiothreitol

Associated data

  • GENBANK/S74354