A COMPARATIVE MOLECULAR DYNAMICS STUDY OF THE …discus/muccc/muccc16/MUCCC16-Gorman.pdf · a...
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A COMPARATIVE MOLECULAR DYNAMICS STUDY OF THE EFFECT
OF ALPHA-TOCOPHEROL AND CHOLESTEROL ON PHOSPHOLIPID
BILAYERS HAVING DIFFERENT LEVELS OF ACYL CHAIN
UNSATURATION
James GormanWabash College
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Background
Phospholipid:• class of lipid• usually contains a phosphate group• hydrophilic head• hydrophobic tail
Bilayer:• Thin membrane made of 2 layers of lipids
Membrane:• barrier between the interior and exterior• nearly all cells have a membrane• cell membranes have hydrophobic interior and hydrophilic interior
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Alpha-Tocopherol (ATOC)
13 Carbon tail
Positive Health benefits:Alzheimer’s DiseaseCancerCataractsHeart Disease
Cholesterol (CHOL)
6 Carbon tail
Health Risks:Cardiovascular DiseaseHeart AttackStrokePeripheral Disease
C27H46O
SolutesC29H50O2
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DPPC SDPC1,2-Dipalmitoyl-sn-glycero-3-phosphocholine
Both 16:063.1 ± 2.2 Å2/molecule
1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine
18:0 and 22:668.2 ± 1.3 Å2/molecule
Lipids
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Solute EffectsDPPC SDPC
Average Lipid Area 63.1 ± 2.3 68.2 ± 1.3
Apparent CHOL area ‐1.76 ± 0.14 ‐4.05 ± 0.32
Apparent ATOC area 24.1 ± 1.9 25.7 ± 2.1
2300
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10 20 30 40 50 60 70 80 90 100 110
Are
a (Å
2 )
Time (ns)
Total Simulation Area vs. Time
atoc_sdpcchol_sdpcatoc_dppcchol_dppcpure_sdpcpure_dppcpure_dppcpure_dppcpure_dppc
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Solute Distribution
• Atoc stays closer to center of the bilayer
• Chol remains slightly farther away from center
• Water mainly stays away from the membrane
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Radial Distribution Functions
Atoc/SDPC
Atoc/DPPC
Chol/SDPC
Chol/DPPC
Radial Distribution Functions
• Have similar distributions• All spend most time near water• Hydrogen bonding
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Interaction Energy
ATOC CHOL
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Order Parameters
• Determine the disorder of a system• Range from 0 to 1• 0 signifies a disordered system• 1 specifies an ordered system
Θ = angle C‐H vector makes with the z‐axis
Scd=<(3/2) Cos2 (Θ)-1/2>
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Solute Effects
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Acknowledgements
Dr. Scott FellerMatt RoarkLucas Evans
NSF