title: Influence of surfactant protein C on the interfacial behavior of phosphatidylethanolamine monolayers.
abstract: In the current work we study with monolayer tensiometry and Brewster angle microscopy (BAM) the surface properties of Dipalmitoleoylphosphatidylethanolamine (DPoPE) films at the air/water interface in presence and absence of specific surfactant protein C (SP-C). DPoPE is used, as it readily forms both lamellar (L(alpha)) and non-lamellar inverted hexagonal (H(II)) phases and appears as a suitable model phospholipid for probing the interfacial properties of distinct lipid phases. At pure air/water interface L(alpha) shows faster adsorption and better surface disintegration than H(II) phase. The interaction of DPoPE molecules with SP-C (predeposited at the interface) results in equalizing of the interfacial disintegration of the both phases (reaching approximately the same equilibrium surface tension) although the adsorption kinetics of the lamellar phase remains much faster. Monolayer compression/decompression cycling revealed that the effect of SP-C on dynamic surface tensions (gamma (max) and gamma (min)) of mixed films is remarkably different for the two phases. If gamma (max) for L(alpha) decreased from the first to the third cycle, the opposite effect is registered for H(II) where gamma (max) increases during cycling. Also the significant decrease of gamma (min) for L(alpha) in SP-C presence is not observed for H(II) phase. BAM studies reveal the formation of more uniform and homogeneously packed DPoPE monolayers in the presence of SP-C.
authors.affiliation: Department of Lipid-Protein Interactions, Institute of Biophysics, Bulgarian Academy of Sciences, 1113, Sofia, Bulgaria. albena@biofac.uni-sofia.bg
authors.forename: Albena
authors.initials: A
authors.lastname: Jordanova
authors.forename: Georgi As
authors.initials: GA
authors.lastname: Georgiev
authors.forename: Svobodan
authors.initials: S
authors.lastname: Alexandrov
authors.forename: Roumen
authors.initials: R
authors.lastname: Todorov
authors.forename: Zdravko
authors.initials: Z
authors.lastname: Lalchev
mesh_terms: D000042:Absorption; D000388:Air; D000818:Animals; D004591:Electrophoresis, Polyacrylamide Gel; D004983:Ethanolamines / Q000737:chemistry*; D005231:Fatty Acids, Unsaturated / Q000737:chemistry*; D007700:Kinetics; D008567:Membranes, Artificial; D037721:Pulmonary Surfactant-Associated Protein C / Q000737:chemistry*; D013499:Surface Properties; D013552:Swine; D014867:Water / Q000737:chemistry
chemical_list: D004983:Ethanolamines; D005231:Fatty Acids, Unsaturated; D008567:Membranes, Artificial; D037721:Pulmonary Surfactant-Associated Protein C; C494000:dipalmitoleoylphosphatidylethanolamine; D014867:Water