title: Molecular interaction studies of peptides using steady-state fluorescence intensity. Static (de)quenching revisited.
abstract: Protein-protein interactions, as well as peptide-peptide and peptide-protein interactions are fields of study of growing importance as molecular-level detail is avidly pursued in drug design, metabolic regulation and molecular dynamics, among other classes of studies. In membranes, this issue is particularly relevant because lipid bilayers potentiate molecular interactions due to the high local concentration of peptides and other solutes.However, experimental techniques and methodologies to detect and quantify such interactions are not abundant. A reliable, fast and inexpensive alternative methodology is revisited in this work. Considering the interaction of two molecules, at least one of them being fluorescent, either intrinsically (e.g. Trp residues) or by grafting a specific probe, changes in their aggregation state may be reported, as long as the fluorophore is sensitive to local changes in polarity, conformation and/or exposure to the solvent. The interaction will probably lead to modifications in fluorescence intensity resulting in a decrease ('quenching') or enhancement ('dequenching'). Although the presented methodology is based on static quenching methodologies, the concept is extended from quenching to any kind of interference with the fluorophore. Equations for data analysis are shown and their applications are illustrated by calculating the binding constant for several data-sets.
authors.affiliation: Centro de Química e Bioquímica, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, Ed C8, 1749-016 Lisboa, Portugal.
authors.forename: Marta M B
authors.initials: MM
authors.lastname: Ribeiro
authors.forename: Henri G
authors.initials: HG
authors.lastname: Franquelim
authors.forename: Miguel A R B
authors.initials: MA
authors.lastname: Castanho
authors.forename: Ana Salomé
authors.initials: AS
authors.lastname: Veiga
mesh_terms: D005453:Fluorescence; D008051:Lipid Bilayers; D010455:Peptides / Q000737:chemistry*; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence
chemical_list: D008051:Lipid Bilayers; D010455:Peptides