Effect of a zwitterionic surfactant (HPS) on the conformation and hemolytic activity of St I and St II, two isotoxins purified from Stichodactyla helianthus - Lanio, Maria E.; Alvarez, Carlos; Martinez, F. D.; Casallanovo, Fábio; Schreier, Shirley; Campos, Ana Maria; Abuin, E.; Lissi, Eduardo (Journal of Protein Chemistry, 2002)