Isolation and partial characterization of three lethal and hemolytic toxins from the sea anemone Actinia cari

Three lethal and hemolytic toxins, caritoxin I, II and III were isolated from the sea anemone Actinia cari. Following controlled autolysis, tentacles were strained through a nylon sieve and thus a crude extract was obtained. The toxins were further purified by Sephadex G-75 gel chromatography. All three toxins which were eluted at the same peak, were separated by ion-exchange chromatography on CM-cellulose. Disc-PAGE revealed electrophoretic homogeneity of caritoxin II. Caritoxin I was obtained in pure form following rechromatography on CM-cellulose. Purified toxins were stable in the pH range 3 - 8. The preliminary determined molecular weight of the toxins was 20 - 25000 daltons. All three toxins are basic proteins. Isoelectric point of caritoxin I was determined as 10.7. The isolated toxins are lethal (LD 5o of caritoxin I is 22 microgram/kg mice, i.v.) and indicate high hemolytic activity with a pH optimum between 8 and 9. Sphingomyelin specifically and irreversibly inhibits the hemolytic activity of caritoxins as well as some other sea anemone cytolytic toxins.