title: Cercospora beticola toxins. VII. Fluorometric study of their interactions with biological membranes.
abstract: The interactions of two beticolins, Cercospora beticola toxins, and of their magnesium complexes with liposomes or plasma membrane were studied. The fluorometric pH titration curves of beticolins in liposomes and in plasma membranes reveal the presence of the dissociated form of beticolins. The concentration of the magnesium complex in these membranes increases at high pH. The partition coefficient of beticolin-1 on liposomes is 3-fold higher than that of beticolin-2 and the fluorescence of both compounds on liposomes is similar. The addition of magnesium to liposomes causes a 40-fold and 20-fold increase in the partition coefficient of beticolin-1 and -2, respectively, as a result of the interactions between membrane, magnesium and beticolins. Beticolins react to a delta pH across the liposome membrane but the formation of the magnesium complex completely abolishes this effect.
authors.affiliation: Unité Associée Phytopharmacie Phytobiologie Cellulaire, INRA-Université de Bourgogne, Dijon, France.
authors.forename: V
authors.initials: V
authors.lastname: Mikes
authors.forename: M L
authors.initials: ML
authors.lastname: Milat
authors.forename: A
authors.initials: A
authors.lastname: Pugin
authors.forename: J P
authors.initials: JP
authors.lastname: Blein
mesh_terms: D001665:Binding Sites; D002462:Cell Membrane / Q000737:chemistry; D005453:Fluorescence; D006576:Heterocyclic Compounds, 4 or More Rings; D006863:Hydrogen-Ion Concentration; D008081:Liposomes; D008274:Magnesium; D009183:Mycotoxins / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D003313:Zea mays
chemical_list: D006576:Heterocyclic Compounds, 4 or More Rings; D008081:Liposomes; D009183:Mycotoxins; C089994:beticolin 2; C089993:beticolin 1; D008274:Magnesium