Lipids. Water vsoil. Water is a Polar Molecule δ + Polarity vs Nonpolarity H O

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1 Water vsil SCBC203 Lipids Jirundon Yuvaniyama, Ph.D. Department of Biochemistry Faculty of Science Mahidol University Figure taken from Figures taken from Polarity vs Nonpolarity Water is a Polar Molecule δ + δ -bonds Figure taken from δ + δ Figure taken from

2 Water is a Polar Molecule δ + ydrocarbon is Nonpolar 0 δ C δ + δ Figure taken from Tetrahedral geometry neutralizes polarity of the bonds. Methane thus has no polarity and cannot form -bond with water. ydrophobic Interaction ydrophobic Interaction G= T S G= T S Figure taken from

3 Lipids Can Form Biomembrane Membranes Create Cells Figure taken from Figure taken from Example Functions of Lipids Compartmentalization by Membrane Lipids Anchoring proteins onto biomembranes Energy storage - triglycerides Facilitating generation of nerve impulses myelin sheath Etc... Six Types of Lipids Terpene derivatives Esters of long-chain alcohols waxes Glycerol esters glycerides Glycerophospholipids Sphingolipids Sterol derivatives steroids

4 Terpenes: Polymers of Isoprene Fatty Acid 3 C C 3 C 3 3 C C 3 C 3 2 C C 2 C 3 C 3 C 3 C 3 C 3 C C 3 3 C C C 3 C 3 C 3 3 Isoprene (C 5 ) β-carotene (C 40 ) Phytol(C 20 ) Dolichol(C ) 2 CC 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 3 Saturated Fatty Acids Stearic acid 18:0 C C 3 - P - Dolichol phosphate Amphipathic molecule Figure taken from Fatty Acid 9 ω-9 C C 2 CC 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 3 Unsaturated Fatty Acids Saturated FA Figure taken from leic acid 18:1ω-9 Unsaturated FA

5 Saturated vs Unsaturated FA Saturated vs Unsaturated FA Stearic acid 18:0 Figure taken from leic acid 18:1ω-9 Saturated fatty acids Saturated and unsaturated fatty acids Kinked structures of unsaturated FA prevent their tight packing, resulting in lower melting point and lower density, comparing with saturated FA of similar chain lengths. Figure taken from Lipid Peroxidation Glycerol C 2 C C 2

6 Glycerides Triacontanoylpalmitate 3C C2 C(C C(C 2 2)16 C 2)163C3 C C(C C(C 2 2)16 C 2)163C3 1-Triacontanol (C30) C(C C2 C(C 2)163C3 2 2)16 C Palmitic acid (C16) 3C 28 C3 14 Monoglyceride Triglyceride Diglyceride Melting point: C Triacontanoylpalmitate (Beeswax) Figures taken from C3 Glycerophospholipids

7 Sphingolipids Figure taken from Blood Group Determinants

8 il/wax cluster Nonpolar lipids Spherical micelles Lipid Aggregates Conical-shaped, amphipathic lipids Critical micelle concentration (CMC) Lipid bilayer liposome Cylindrical-shaped, amphipathic lipids Scuba Diver Scuba divers put on a weight belt to adjust the density of their bodies to match that of the sea. Figures taken from Spermaceti il Saponification Na or K C 2 C 2 C(C 2 ) 16 C 3 2 C(C 2 ) 16 C 3 C 2 2 C(C 2 ) 16 C 3 Sperm whales adjust the degree of saturation in their lipid molecules for density adjustment to match that of the sea. Figure taken from These fatty acids can wash away oily (nonpolar) substances from our bodies or other materials, ie. being soap or detergents.

9 Micelle Formation Lipid Bilayer Formation Adapted from Figures taken from Lipid Bilayer is Part of Liposome Lipid Bilayer Formation Figure taken from Figures taken from Phospholipids_aqueous_solution_structures.svg.png

10 Amphipathic Lipid Aggregates Steroids Aqueous cavity C 3 C 3 C 3 Estradiol Testosterone C 3 3 C C 3 C C 3 3 C C 3 C 3 C 3 Spherical Lipid Micelle Bilayer Liposome Cholic acid Cholesterol Cholesterol Cholesterol inserts itself in bilayer membranes with its polar facing outward. Its rigid structure increases membrane rigidity. Figure taken from Lipid Movements on Bilayer Figure taken from Three types of lipid movements on bilayer membrane with average rates of movements shown. Transverse diffusion (flip-flop) occurs at the slowest rate due to thermodynamically unfavorable flipping of polar head through internally nonpolar region of the bilayer.

11 Asymmetric Distribution of Membrane Lipids Recruitment of ther Biomolecules on Lipid Bilayer Total phospholipids uter leaflet Sphingomyelin Phosphatidylcholine Phosphatidylethanolamine Phosphatidylinositol Phosphatidylserine This asymmetric distribution of lipids on both sides of cell membranes is an evident for flippases enzymes that flip lipids from one side to the other. Inner leaflet Figure taken from Fluid-Mosaic Membrane Structure Summary Basic structure of lipids ydrocarbon nonpolar/hydrophobic May contain polar head group amphipathic May contain double bond(s), ester, amide, or ether linkage(s) Properties of lipids Lipid aggregation no polymerization Formation of micelles or bilayer/liposome Some functions of lipids Figure taken from