Purification and partial characterization of a cohaemolysin (CAMP-factor) produced by Streptococcus canis

A cohaemolysin from the culture supernate of a canine pathogenic group G streptococcus (S. canis) was purified to electrophoretic homogeneity. The purification procedure involved ammonium sulphate precipitation, ultrafiltration, gel filtration and preparative isoelectric focusing. The cohaemolysin consisted of a single polypeptide chain, 18.6 kDa, with an isoelectric point at pH 5.1. The protein reacted with an homologous antiserum, appeared to be trypsin-sensitive and relatively heat-stable. The cohaemolysin did not show any non-specific IgG binding activities.