Isolation and structure of the bacterial sex pheromone, cAD1, that induces plasmid transfer in Streptococcus faecalis

The Streptococcus faecalis sex pheromone cAD1, which is involved in the conjugative transfer of the hemolysin plasmid pAD1, has been isolated and its structure determined. Its Mr is 818 and its amino acid sequence is H-Leu-Phe-Ser-Leu-Val-Leu-Ala-Gly-OH. A replicate of the pheromone synthesized by the liquid-phase method showed the same biological activity and chromatographic behavior as the isolated cAD1. Pheromone activity was detectable at a concentration of approximately 5 X 10(-11) M.