title: Effect of human serum albumin upon the permeabilizing activity of sticholysin II, a pore forming toxin from Stichodactyla heliantus.
abstract: Sticholysin II (St II) is a haemolytic toxin isolated from the sea anemone Stichodactyla helianthus. The high haemolytic activity of this toxin is strongly dependent on the red cell status and the macromolecule conformation. In the present communication we evaluate the effect of human serum albumin on St II haemolytic activity and its capacity to form pores in the bilayer of synthetic liposomes. St II retains its pore forming capacity in the presence of large concentrations (up to 500 μM) of human serum albumin. This effect is observed both in its capacity to produce red blood cells haemolysis and to generate functional pores in liposomes. In particular, the capacity of the toxin to lyse red blood cells increases in the presence of human serum albumin (HSA). Regarding the rate of the pore forming process, it is moderately decreased in liposomes and in red blood cells, in spite of an almost total coverage of the interface by albumin. All the data obtained in red cells and model membranes show that St II remains lytically active even in the presence of high HSA concentrations. This stubbornness can explain why the toxin is able to exert its haemolytic activity on membranes immersed in complex plasma matrixes such as those present in living organisms.
authors.affiliation: Departamento de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaiso, Chile.
authors.forename: Gloria
authors.initials: G
authors.lastname: Celedón
authors.forename: Gustavo
authors.initials: G
authors.lastname: González
authors.forename: Felipe
authors.initials: F
authors.lastname: Gulppi
authors.forename: Fabiola
authors.initials: F
authors.lastname: Pazos
authors.forename: María E
authors.initials: ME
authors.lastname: Lanio
authors.forename: Carlos
authors.initials: C
authors.lastname: Alvarez
authors.forename: Cristian
authors.initials: C
authors.lastname: Calderón
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Montecinos
authors.forename: Eduardo
authors.initials: E
authors.lastname: Lissi
mesh_terms: D000818:Animals; D002463:Cell Membrane Permeability / Q000187:drug effects; D003064:Cnidarian Venoms / Q000302:isolation & purification / Q000378:metabolism*; D004912:Erythrocytes / Q000187:drug effects / Q000473:pathology; D006461:Hemolysis / Q000187:drug effects*; D006801:Humans; D008081:Liposomes / Q000378:metabolism; D052899:Pore Forming Cytotoxic Proteins / Q000302:isolation & purification / Q000378:metabolism*; D012615:Sea Anemones / Q000737:chemistry*; D012709:Serum Albumin / Q000378:metabolism*
chemical_list: D003064:Cnidarian Venoms; D008081:Liposomes; D052899:Pore Forming Cytotoxic Proteins; D012709:Serum Albumin; C404794:sticholysin II