Isolation and structure of theStreptococcus faecalissex pheromone, cAM373

Abstract
The Streptococcus faecalis sex pheromone, cAM373, which induces a mating response of donor cells harboring plasmid pAM373 and is also produced by Staphylococcus aureus, was isolated and its structure determined. Supernatant from an overnight culture of a recipient strain was subjected to successive purification procedures, and 4.4 μg cAM373 was obtained. The isolated pheromone showed activity at a concentration as low as 5 × 10−11 M. Sequence analysis indicated that cAM373 was a heptapeptide, H‐Ala‐Ile‐Phe‐Ile‐Leu‐Ala‐Ser‐OH, and that its M r was 733. A synthetic replicate of the peptide showed the same biological activity and chromatographic behavior as the native cAM373.