title: Kinetics of lipid-membrane binding and conformational change of L-BABP.
abstract: We designed an experimental approach to differentiate the kinetics of protein binding to a lipid membrane from the kinetics of the associated conformational change in the protein. We measured the fluorescence intensity of the single Trp6 in chicken liver bile acid-binding protein (L-BABP) as a function of time after mixing the protein with lipid membranes. We mixed the protein with pure lipid membranes, with lipid membranes in the presence of a soluble quencher, and with lipid membranes containing a fluorescence quencher attached to the lipid polar head group. We fitted simultaneously the experimental curves to a three-state kinetic model. We conclude that in a first step, the binding of L-BABP to the interfacial region of the anionic lipid polar head groups occurred simultaneously with a conformational change to the partly unfolded state. In a second slower step, Trp6 buried within the polar head group region, releasing contacts with the aqueous phase.
authors.affiliation: Centro de Investigaciones en Química Biológica de Córdoba, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, Córdoba, Argentina.
authors.forename: Vanesa
authors.initials: V
authors.lastname: Galassi
authors.forename: Verónica
authors.initials: V
authors.lastname: Nolan
authors.forename: Marcos Ariel
authors.initials: MA
authors.lastname: Villarreal
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Perduca
authors.forename: Hugo L
authors.initials: HL
authors.lastname: Monaco
authors.forename: Guillermo G
authors.initials: GG
authors.lastname: Montich