Effect of pH on the Conformation and Biological Activity of Clostridium septicum Alpha-toxin, a Pore-forming Hemolysin

The effects of pH on the pore-forming Clostridium septicum alpha-toxin that causes myonecrosis was assessed at pH 5.0, 7.0 and 9.0 by measuring circular dichroism and its biological activity. Incubation of the toxin at pH 5.0 increased the hemolytic activity measured in murine red blood cells. On the other hand, incubation of the toxin at pH 9.0 drastically reduces the biological activity of the toxin by five-fold. This study presents the first evidence of the effect of pH on the functional properties of alpha-toxin directly related to the common disease caused by C. septicum in animals and humans i.e. traumatic and non traumatic gas gangrene.