Biomembranes and biosurfactants – Neutron reflectometry to study complexation of phospholipids and saponins
Biomembranes and biosurfactants – Neutron reflectometry to study complexation of phospholipids and saponins
The interactions between model phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and biosurfactant Quillaja Bark Saponin (QBS) and various triterpene saponins have been studied using simple models of biological membranes [1-3]. QBS is known to interact strongly with the latter, exertin...
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Personal Name(s): | Wojciechowski, Kamil |
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Orczyk, Marta / Marcinkowski, Kuba / Kobiela, T. / Geue, Thomas / Trapp, Marcus / Gutberlet, Thomas | |
Contributing Institute: |
JCNS-FRM-II; JCNS-FRM-II High Brilliance Source; JCNS-HBS |
Imprint: |
2016
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Conference: | Bunsen Discussion Meeting Neutrons in Chemistry, Bielefeld (Germany), 2016-07-25 - 2016-07-27 |
Document Type: |
Conference Presentation |
Research Program: |
FRM II / MLZ Jülich Centre for Neutron Research (JCNS) |
Subject (ZB): | |
Publikationsportal JuSER |
The interactions between model phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and biosurfactant Quillaja Bark Saponin (QBS) and various triterpene saponins have been studied using simple models of biological membranes [1-3]. QBS is known to interact strongly with the latter, exerting a number of haemolytic, cytotoxic and anti-microbial actions. The interaction of QBS dissolved in the subphase with DPPC monolayers and silicon-supported bilayers was studied using surface pressure relaxation and surface dilatational rheology combinedwith quartz crystal microbalance (QCM) and neutron reflectivity. We show that the penetration studies using high surface activity (bio)surfactants should be performed by a subphase exchange, not by spreading onto the surfactant solution. In contrast to the synthetic surfactants of similar surface activity, QBS does not collapse DPPC mono- and bilayers, but penetrates them, improving their surface dilatational elastic properties even in the highly compressed solid state. In mixed model lipids of cholesterol and DPPC the oleanolic acidtype saponins (α-hederin and hederacoside C)were shown to form1:1 complexes with lipids. The complexes with cholesterol aregenerally stronger than those with DPPC. These saponin–lipid interactions were studied in confined environment using Langmuir monolayers of DPPC and DPPC/cholesterol with monolayer relaxation, surface dilational rheology, fluorescence microscopy and neutron reflectometry (NR). It is shown that all three saponins are able to penetrate pure DPPC and mixed DPPC/cholesterolmonolayers. Overall,the effect of the saponins on the model lipid monolayers does not fully correlate with the lipid–saponin complex formation in homogeneous solution. The combined bulk and monolayer results are discussed in view of the role of confinement in modulating the saponin–lipid interactions and possible mechanism of membranolytic activity of saponins. |