Transcript The effect of resorcinolic lipids on biological membranes Magdalena Siwko Resorcinolic lipids • Found in higher plants (cashew nut, Ginkgo biloba, wheat bran, rye, barley),

The effect of resorcinolic lipids
on biological membranes
Magdalena Siwko
Resorcinolic 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) 4.5-8.5mM
• Potential applications: medicine,
nutrition, agriculture
Biological activity of resorcinols
On membranes:
 Bacteriostatic and fungistatic
activity
 Non-toxic to higher animals
 Protect
cellular lipids from
oxidation processes
-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”
Questions:
 How resorcinolic lipids affect phospholipid bilayers?
 Is this dependent on the length of alkyl tail?
 How do resorcinols distribute within a DMPC bilayer?
Bilayer formation in water
~30-35 SPC/lipid
64 RES11
64 DMPC
64 RES19
25-30mol%
28RES : 64DMPC or 112 RES : 256 DMPC
DMPC + RES11
DMPC + RES19
DMPC +
RES25
•Temperature: 323K
Bilayer formation RES19/DMPC
Mass density distribution
Pure DMPC
DMPC+RES11
water
DMPC
phosphoryl
RES
RES-OH
carbonyl
DMPC+RES19
DMPC+RES25
Resorcinols induce packing of lipid tails
Summary
• 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
Incorporation of resorcinolic lipids in the
DMPC bilayer
Temperature: 323K
RES11
RES19
RES25
DMPC
~35-49 SPC/lipid
30mol% (21RES:64DMPC or 112RES:256DMPC)
Res11/DMPC bilayers (no micelle formation)
0 ns
200 ns
10 ns
280 ns
Simulation time: 340 ns
300 ns
Res19/DMPC (micelle formation)
Severe membrane disruption
QuickTime™ and a
YUV420 codec decompressor
are needed to see this picture.
Simulation time: 175 ns
Res25/DMPC (micele bilayer interaction)
Formation of gel phase domain
QuickTime™ and a
YUV420 codec decompressor
are needed to see this picture.
Simulation time: 90 ns
Steps in the pore-forming process of the
incorporation
Summary
 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