title: Combined effect of synthetic protein, Mini-B, and cholesterol on a model lung surfactant mixture at the air-water interface.
abstract: The overall goal of this work is to study the combined effects of Mini-B, a 34 residue synthetic analog of the lung surfactant protein SP-B, and cholesterol, a neutral lipid, on a model binary lipid mixture containing dipalmitolphosphatidylcholine (DPPC) and palmitoyl-oleoyl-phosphatidylglycerol (POPG), that is often used to mimic the primary phospholipid composition of lung surfactants. Using surface pressure vs. mean molecular area isotherms, fluorescence imaging and analysis of lipid domain size distributions; we report on changes in the structure, function and stability of the model lipid-protein films in the presence and absence of varying composition of cholesterol. Our results indicate that at low cholesterol concentrations, Mini-B can prevent cholesterol's tendency to lower the line tension between lipid domain boundaries, while maintaining Mini-B's ability to cause reversible collapse resulting in the formation of surface associated reservoirs. Our results also show that lowering the line tension between domains can adversely impact monolayer folding mechanisms. We propose that small amounts of cholesterol and synthetic protein Mini-B can together achieve the seemingly opposing requirements of efficient LS: fluid enough to flow at the air-water interface, while being rigid enough to oppose irreversible collapse at ultra-low surface tensions.
authors.affiliation: Department of Chemical Engineering, University of Kansas, KS 66045, United States.
authors.forename: Aishik
authors.initials: A
authors.lastname: Chakraborty
authors.affiliation: Department of Chemical Engineering, University of Kansas, KS 66045, United States.
authors.forename: Erica
authors.initials: E
authors.lastname: Hui
authors.affiliation: Department of Medicine, Harbor UCLA Medical Center - LA BioMed, CA 90502, United States; Department of Physiology and Biophysics, University of California, Irvine, CA 92697, United States.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Waring
authors.affiliation: Department of Chemical Engineering, University of Kansas, KS 66045, United States. Electronic address: prajnadhar@ku.edu.
authors.forename: Prajnaparamita
authors.initials: P
authors.lastname: Dhar
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D000388:Air; D002784:Cholesterol / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D008168:Lung / Q000737:chemistry; D008567:Membranes, Artificial; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D010715:Phosphatidylglycerols / Q000737:chemistry; D037701:Pulmonary Surfactant-Associated Protein B / Q000138:chemical synthesis / Q000737:chemistry*; D013499:Surface Properties; D013500:Surface Tension; D014867:Water / Q000737:chemistry
chemical_list: D008051:Lipid Bilayers; D008567:Membranes, Artificial; D010455:Peptides; D010715:Phosphatidylglycerols; D037701:Pulmonary Surfactant-Associated Protein B; D014867:Water; D015060:1,2-Dipalmitoylphosphatidylcholine; D002784:Cholesterol
keywords: Cholesterol; Compressibility; Line tension; Lung surfactants; Mini-B; Surface tension