title: A versatile method for determining the molar ligand-membrane partition coefficient.
abstract: A novel method for the quantitative assessment of the membrane partitioning of a ligand from the aqueous phase is described, demonstrated here with the thoroughly studied antipsychotic chlorpromazine (CPZ). More specifically, collisional quenching of the fluorescence of a pyrene labeled fluorescent lipid analog 1-palmitoyl-2[10-(pyren-1-yl)]decanoyl-sn-glycero-3-phosphocholine (PPDPC) by CPZ was utilized, using 1-palmitoyl-2-oleyl-sn-glycero-3-phosphocholine and -serine (POPC and POPS) liposomes as model membranes. The molar partition coefficient is obtained from two series of titrations, one with constant [phospholipid] and increasing [drug] and the other with constant [drug] and varying total [phospholipid], the latter further comprising of large unilamellar vesicles (LUVs) of POPC/POPS/PPDPC at a constant concentration of 10 microM and indicated concentrations of POPC/POPS LUVs. Notably, the approach described is generic and can be employed in screening for the membrane partitioning of compounds, providing that a suitable fluorescence parameter can be incorporated into one population of liposomes utilized as model membranes.
authors.affiliation: Helsinki Biophysics and Biomembrane Group, Medical Biochemistry, Institute of Biomedicine, University of Helsinki, P.O. Box 63, 00014 Helsinki, Finland.
authors.forename: Mikko J
authors.initials: MJ
authors.lastname: Parry
authors.forename: Arimatti
authors.initials: A
authors.lastname: Jutila
authors.forename: Paavo K J
authors.initials: PK
authors.lastname: Kinnunen
authors.forename: Juha-Matti
authors.initials: JM
authors.lastname: Alakoskela
mesh_terms: D014150:Antipsychotic Agents / Q000737:chemistry*; D002746:Chlorpromazine / Q000737:chemistry*; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry; D008024:Ligands; D008081:Liposomes; D008563:Membrane Lipids / Q000737:chemistry*; D015394:Molecular Structure; D010713:Phosphatidylcholines / Q000737:chemistry*; D010718:Phosphatidylserines / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D014867:Water / Q000737:chemistry
chemical_list: D014150:Antipsychotic Agents; D005456:Fluorescent Dyes; D008024:Ligands; D008081:Liposomes; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D010718:Phosphatidylserines; D014867:Water; C050294:1-palmitoyl-2-oleoylglycero-3-phosphoserine; C021248:1-palmitoyl-2-pyrenedecanoylphosphatidylcholine; C028694:1-palmitoyl-2-oleoylphosphatidylcholine; D002746:Chlorpromazine