Streptolysin S (SLS) is a small, non-immunogenic, peptide. This means that no commercial antibody against it is available and the peptide is too small for reliable mass spectrometry detection. It is heavily post-translationally modified and is the product of a complex operon. Its exact mode-of-action is still not yet fully clarified. In a previous publication, we were able to show that SLS is neutralized by phosphatidylcholine as well as sphingomyelin liposomes [1]. However, given the poor characterization of SLS, its unavailability from commercial providers and its extremely tedious purification, the mechanistic details of the SLS neutralization will require an extensive a project of its own and are beyond the scope of the current study.
The experiments were performed using different bacterial supernatant batches and results were remarkably consistent.