title: Chondroitin sulfate interacts mainly with headgroups in phospholipid monolayers.
abstract: Sulfated glycosaminoglycans are precursors of the extracellular matrix used to treat diseases related to blood clotting and degenerative joint diseases. These medical applications have been well established, but the mode of action at the molecular level, which depends on the interaction with cell membranes, is not known in detail. In this study, we investigated the interaction between chondroitin sulfate (CS) and phospholipid monolayers that mimic cell membranes. From surface pressure isotherms and polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS), CS was found to interact mainly with the polar groups of dipalmitoyl phosphatidylcholine (DPPC) and dipalmitoyl phosphatidylglycerol (DPPG), with negligible penetration into the hydrophobic tails and only small changes in monolayer elasticity for the packing corresponding to a real cell membrane. The changes in surface pressure and surface potential isotherms depended on CS concentration and on the time allowed for its adsorption onto the monolayer, which points to a dynamic adsorption-desorption process. The charge of the phospholipid was also relevant, since CS induced order into DPPC monolayers while the opposite occurred for DPPG, according to the PM-IRRAS spectra. In summary, interaction with polar groups is responsible for the CS effects on model cell membranes.
authors.affiliation: Institute of Environmental, Chemical and Pharmaceutical Sciences, Federal University of São Paulo, UNIFESP, Diadema, SP, Brazil. Electronic address: lceridorio@yahoo.com.
authors.forename: Lucinéia F
authors.initials: LF
authors.lastname: Ceridório
authors.affiliation: Institute of Environmental, Chemical and Pharmaceutical Sciences, Federal University of São Paulo, UNIFESP, Diadema, SP, Brazil.
authors.forename: Luciano
authors.initials: L
authors.lastname: Caseli
authors.affiliation: Institute of Physics of São Carlos, University of São Paulo, USP, São Carlos, SP, Brazil.
authors.forename: Osvaldo N
authors.initials: ON
authors.lastname: Oliveira
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D000327:Adsorption; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002809:Chondroitin Sulfates / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D008563:Membrane Lipids / Q000737:chemistry* / Q000378:metabolism; D008567:Membranes, Artificial; D010715:Phosphatidylglycerols / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry* / Q000378:metabolism; D011312:Pressure; D013055:Spectrophotometry, Infrared / Q000379:methods; D013499:Surface Properties
chemical_list: D008563:Membrane Lipids; D008567:Membranes, Artificial; D010715:Phosphatidylglycerols; D010743:Phospholipids; D015060:1,2-Dipalmitoylphosphatidylcholine; D002809:Chondroitin Sulfates; C030345:1,2-dipalmitoylphosphatidylglycerol
keywords: Cell membrane model; Chondroitin sulfate; Langmuir monolayers; PM-IRRAS spectroscopy