title: Reduced pH induces an inactive non-native conformation of the monomeric bothropstoxin-I (Lys49-PLA2).
abstract: Bothropstoxin-I (BthTx-I), a Lys49-PLA(2) from Bothrops jararacussu venom, permeabilizes membranes by a non-hydrolytic Ca(2+)-independent mechanism. The BthTx-I showed activity against liposomes including 10% and 50% negatively charged lipids at pH 7.0, but not at pH 5.0. Nevertheless, ultracentrifugation and FRET demonstrated that at pH 5.0 the BthTx-I is bound to 50% negatively charged membranes. ANS binding identified a non-native monomeric conformation at pH 5.0, suggesting that tertiary structure alterations result in activity loss of the BthTx-I at low pH.
authors.affiliation: Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil. arthurdeoliveira@ffclrp.usp.br
authors.forename: Arthur H C
authors.initials: AH
authors.lastname: de Oliveira
authors.forename: Tatiana L
authors.initials: TL
authors.lastname: Ferreira
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Ward
mesh_terms: D003435:Crotalid Venoms / Q000737:chemistry* / Q000235:genetics; D031541:Fluorescence Resonance Energy Transfer; D006863:Hydrogen-Ion Concentration; D008081:Liposomes; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D014461:Ultracentrifugation
chemical_list: D003435:Crotalid Venoms; D008081:Liposomes; C078097:bothropstoxin