We determined the bindings of several lipids such as cholesterol (CHOL), 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), dioctadecyldimethyl-ammoniumbromide (DDAB), and dioleoylphosphatidylethanolamine (DOPE) to β-lactoglobulin (β-LG) at physiological conditions. FTIR, CD, and fluorescence spectroscopic methods as well as molecular modeling were used to determine the binding of lipid-protein complexes. Structural analysis showed that lipids bind β-LG via both hydrophilic and hydrophobic interactions with overall binding constants of K(CHOL-β-LG) = 6.0 (±0.6) × 10(3) M(-1), K(DOPE-β-LG) = 6.5 (±0.7) × 10(3) M(-1), K(DDAB-β-LG) = 1.6 (±0.3) × 10(4) M(-1), and K(DOTAP-β-LG) = 2.2 (±0.67) × 10(4) M(-1). The number of lipid bound per protein molecule (n) was 0.8 (CHOL), 0.7 (DOPE), 1.0 (DDAB), and 1.3 (DOTAP). Molecular modeling showed the participation of several amino acid residues in lipid-protein complexation with the order of binding DOTAP > DDAB > DOPE > CHOL. Alterations of the protein conformation were observed in the presence of lipids with a minor decrease in β-sheet and an increase in turn structure.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.