Purification and characterization of cAMP-factor from Streptococcus agalactiae by hydrophobic interaction chromatography and chromatofocusing.

CAMP-factor from Streptococcus agalactiae (group B streptococcus) was purified 60-fold from the culture supernatant to electrophoretic homogeneity in 57% yield. The purification procedure involved ammonium sulphate precipitation, ultrafiltration, hydrophobic interaction chromatography on Octyl-Sepharose and chromatofocusing on polybuffer exchanger PBE 94. The purified CAMP-factor consists of a single polypeptide chain with an apparent molecular weight of 25 kD and an isoelectric point of 8.9. The properties of the CAMP-factor demonstrated by charge-shift electrophoresis were consistent with those of an amphiphilic polypeptide.