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The effect of resorcinolic lipids on biological membranes
Magdalena Siwko
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Resorcinolic lipidsResorcinolic lipids
• Found in higher plants (cashew nut, Ginkgo biloba, wheat bran, rye, barley), lower plants (algae, mosses, fungi), microbial organisms (bacteria)
• Tail length (11-25) and degree of unsaturation (0-4) varies.
• Very low critical micelle concentration (CMC) 4.5-8.5M
• Potential applications: medicine, nutrition, agriculture
• Found in higher plants (cashew nut, Ginkgo biloba, wheat bran, rye, barley), lower plants (algae, mosses, fungi), microbial organisms (bacteria)
• Tail length (11-25) and degree of unsaturation (0-4) varies.
• Very low critical micelle concentration (CMC) 4.5-8.5M
• Potential applications: medicine, nutrition, agriculture
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Biological activity of resorcinolsBiological activity of resorcinols
Bacteriostatic and
fungistatic activity
Non-toxic to higher
animals
Protect cellular lipids from
oxidation processes
On membranes:-pre-incorporated increase the
resistance of the liposome to
water and small solutes
-incorporated into the suspension
of liposomes increase a release
of ions, small solutes such as
glucose, change transport of
water -”surfactant-like effect”
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Questions: Questions:
How resorcinolic lipids affect phospholipid bilayers? Is this dependent on the length of alkyl tail? How do resorcinols distribute within a DMPC
bilayer?
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Bilayer formation in water
64 RES19
64 RES11
64 DMPC
DMPC + RES19
DMPC + RES11
DMPC +
RES25
~30-35 SPC/lipid
•Temperature: 323K
25-30mol% 28RES : 64DMPC or 112 RES : 256 DMPC
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Bilayer formation RES19/DMPCBilayer formation RES19/DMPC
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Mass density distributionMass density distribution
water
phosphoryl
RES
RES-OH
carbonyl
DMPC
Pure DMPC
DMPC+RES19DMPC+RES25
DMPC+RES11
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Resorcinols induce packing of lipid
tails
Resorcinols induce packing of lipid
tails
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SummarySummary• Bilayer formation largely unaffected by resorcinol
• Asymmetric distribution between leaflets (cluster formation) but no clear domains
• Resorcinols increase order parameters
• Interaction of RES hydroxyl groups with DMPC glycerol the ester groups
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Incorporation of resorcinolic lipids in the DMPC bilayer
DMPCRES19
RES11
RES25
30mol% (21RES:64DMPC or 112RES:256DMPC)
Temperature: 323K
~35-49 SPC/lipid
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Res11/DMPC bilayers (no micelle
formation)
Res11/DMPC bilayers (no micelle
formation)
Simulation time: 340 ns
0 ns 10 ns 200 ns
280 ns 300 ns
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Res19/DMPC (micelle formation)
Severe membrane disruption
Res19/DMPC (micelle formation)
Severe membrane disruption
Simulation time: 175 ns
QuickTime™ and aYUV420 codec decompressor
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Res25/DMPC (micele bilayer interaction)Formation of gel phase domain
Res25/DMPC (micele bilayer interaction)Formation of gel phase domain
Simulation time: 90 ns
QuickTime™ and aYUV420 codec decompressor
are needed to see this picture.
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Steps in the pore-forming process of the incorporation
Steps in the pore-forming process of the incorporation
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SummarySummary
Alternative mechanisms of incorporation lead to marked
differences in disruption.
Alternative final phases depending on chain length:
a) lamellar - RES11,
b) hexagonal - RES19,
c) lamellar with gel phase domain - RES25
Final bilayers asymmetric: much longer simulation times
required for equilibration
Alternative mechanisms of incorporation lead to marked
differences in disruption.
Alternative final phases depending on chain length:
a) lamellar - RES11,
b) hexagonal - RES19,
c) lamellar with gel phase domain - RES25
Final bilayers asymmetric: much longer simulation times
required for equilibration