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Author(s): Maria Joao Moreno
Margarida Bastos
Adrian Velazquez Campoy
Title: Partition of amphiphilic molecules to lipid bilayers by isothermal titration calorimetry
Issue Date: 2010
Abstract: The partition of the amphiphile sodium dodecyl sulfate (SDS) between an aqueous solution and a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayer was followed by isothermal titration calorimetry (ITC) as a function of the total concentration of SDS. It was found that the obtained partition coefficient is strongly affected by the ligand concentration, even after correction for the charge imposed in the bilayer by the bound SDS. The partition coefficient decreased as the total concentration of SDS increased, with this effect being significant for local concentrations of SDS in the lipid bilayer above 5 molar%. At those high local concentrations, the properties of the lipid bilayer are strongly affected, leading to nonideal behavior and concentration-dependent apparent partition coefficients. It is shown that with the modern ITC instruments available, the concentrations of SDS can be drastically reduced while maintaining a good signal-to-noise ratio. The intrinsic parameters of the interaction with unperturbed membranes can be obtained from the asymptotic behavior of the apparent parameters as a function of the ligand concentration for both nonionic and ionic solutes. A detailed analysis is performed, and a spreadsheet is provided to obtain the interaction parameters with and without correction for electrostatics.
Subject: Química aplicada, Química física, Química
Applied chemistry, Physical chemistry, Chemical sciences
Scientific areas: Ciências exactas e naturais::Química
Natural sciences::Chemical sciences
Document Type: Artigo em Revista Científica Internacional
Rights: restrictedAccess
Appears in Collections:FCUP - Artigo em Revista Científica Internacional

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