BCH210 – Lipids and Membranes
Lecture 1 – Lipid Structure & Properties
Why are membranes important?
-‐ Protection
-‐ Selectively permeable (No nutrition in, no O2 in, no waste out – all permeable not good either)
-‐ Specialization
-‐ Compartmentalize genetic material so it stays distinct
Lecture 1 Overview – Lipid structure and properties
-‐ Review structure and properties of fatty acids
-‐ Review structure and properties of the most common lipid found in membranes
o Glycerophospholipids
o Sphingolipids
o Cholesterol
-‐ Describe the role of lipids in health and disease
Biological Lipids!
Biological lipids
LIPIDS
Fatty Acids Steroids
Waxes Eicosanoids Triglycerides
Glycerophospholipids* Sphingolipids* Cholesterol*
* Primary lipids in biological membranes
-‐ Fatty acids is a much more diverse family
*Primary lipids in biological membranes
6!
General properties of lipids
-‐ Solubility
o Low in water and high in non-polar solvents
-‐ Hydrophobic and/or amphipathic
o Contain both polar and non-polar groups Saturated Fatty Acid Structure!
-‐ Self-assemble in water
Polar
o Hydrophobic effect and van der Waals interactions Non-polar Carboxylic
Hydrocarbon tail acid
Saturated fatty acid structure H H H H H H H H H H H H H H H O
=
H!C!C!C!C!C!C!C!C!C!C!C!C!C!C!C!C
!
OH
-‐ Alkane adopts lowest energy form based on steric clash H H H H H H H H H H H H H H H
-‐ Physiological pH most acids are deprotonated ∴ makes (CH2)n H H H H H H H H
them more polar H H
H3C
-‐ Extended conformation = zigzag H H
H H H H H H H H
CH3
‘Anti’ conformation Extended conformation
Saturated fatty acid nomenclature
Unsaturated Fatty Acids!
is most stable is most stable 8!
-‐ 4 ways to name a fatty acid but only talk about 3 H H
1. Symbol
Oleic Acid
a. [#C]:[# of double bonds]
b. 18:0 O
2. Systematic name OH
a. Octadecanoic acid
3. Common name
a. Steric acid
• Double bonds almost always in cis conformation
• Results in a kink in structure
10!
,Unsaturated fatty acids
-‐ Double bonds almost always in cis conformation
-‐ Results in a “kink” in structure
Mono-unsaturated fatty acids
-‐ Symbol
o 18:1
-‐ Systematic name
o 9-octadecenoic acid
-‐ Common name
o Oleic acid
Poly-unsaturated fatty acids (PUFAs)
-‐ Symbol
o 18:2
-‐ Systematic name
o 9,12-octadecadienoic acid
-‐ Common name
Packing
o Linoleicofacid
Fatty Acids
Packing of fatty acids
Fatty Acid Properties!
3 stearate 2 stearate + 1 oleate Carbons: Common Melting
-‐ Disrupted packing in 2 stearate + 1 oleae double bonds Name point
13! C16:0 Palmitate 63 °C
Fatty acid properties
C18:0 Stearate 70 °C
-‐ Understand and know that an introduction of a double bond
can cause significant decrease in melting point C16:1 Palmitoleate -0.5 °C
-‐ Melting point reflects how stable the structure is C18:1 Oleate 13 °C
C18:2 Linoleate -9.0 °C
Fatty acids in health and disease
-‐ Fatty acid intake impacts cardiovascular health 14!
Partial Hydrogenation!
o Saturated fatty acids =↑ disease
o Unsaturated fatty acids =↓ disease Melting Temp
O
-‐ Not all unsaturated fatty acids are good
OH
o Hydrogenation of unsaturated fats during food -9°C
Vegetable Oil
processing produces unhealthy fatty acids Healthy but impractical for (fast) food industry
Partial hydrogenation “Partial Hydrogenation”
-‐ Vegetable oil H2 (limiting)
o Healthy but impractical for (fast) food industry O
45°C
o Melting temperature -9°C OH
-‐ Elaidic acid – trans fatty acid Elaidic Acid – Trans Fatty Acid
o Good for baking and long shelf life but Great for baking + long shelf-life but unhealthy
*worse than saturated fatty acids*
unhealthy 16!
, o Worse than saturated fatty acids
o Melting temperature 45°C
-‐ Converting vegetable oil into elaidic acid by partial hydrogenation limiting H2 goes from a cis bond to a
trans dramatically increases the melting temperature
Some Fatty Acids are Essential!
Some fatty acids are essential
• Required forfor
-‐ Required normal
normalhealth butcannot
health but cannot
be be made
made
– We cannot
o Wesynthesize doubledouble
cannot synthesize bonds pastpast
bonds C9*C9*
o Thus, must acquire from diet O
-‐ Animals
• Animals need
need twoEFAs
two EFAsfrom
from diet
diet: Fish Oil
HO
!-Linolenic acid (18:3 "3)
3
O
Eicosapentaenoic acid (20:5 "3)
"-Linolenic Acid = Omega-3 Fatty Acid 3
HO
O O
Docosahexanoic acid (22:6 "3)
* !2
HO 3
-O
!3 ! - anti-inflammatory
Linoleic Acid = Omega-6 Fatty Acid
O
Linoleic acid (18:2 !6)
O Vegetable Oil
!6 6
*
HO
O
-O Arachidonic acid (20:4 !6)
! 17! 6
HO
- pro-inflammatory
Fatty acids are the “tails” of membrane lipids
-‐ In membranes fatty acids are attached to
A healthy diet has a balance of ω3 to ω6 18!
phosphate containing head group
1. Glycerophospholipids
Glycerophospholipids
2. Sphingolipids
General Structure!
Glycerophospholipids general structure
Glycerophospholipids
Headgroup
• Glycerophospholipids are the most
abundant membrane lipids in cells 20!
Glycerophospholipids
Glycerophospholipids
– Based on structure of glycerol
-‐ Glycerophospholipids are the most abundant membrane lipids in cells
o Based on structure of glycerol Fatty Acyl Chains
HO HO Glycerol backbone
CH2 CH2
HO C H HO C H O
H2C OH H2C O P O-
O-
Glycerol Glycerol-3-Phosphate
21!
Glycerophospholipid properties Phosphate Head Group
-‐ Constant
o Glycerol & phosphate 22!
-‐ Variable
, o Fatty acid tails (length, degree of unsaturation)
o Head groups (size, charge)
Neutral Glycerophospholipids Anionic Glycerophospholipids
Neutral glycerophospholipids Anionic Glycerophospholipids
-1 +1
Sphing
-1 +1
• Sphingolipids are the
of membrane lipids
– Based on structure of s
PC and PE are zwitterionic (net neutral) 25!
26!
Sphingolipids Cholesterol
-‐ Sphingolipids are the second major class of membrane lipids
o Based on structure of sphingosine (not glycerol)
Sphi
o Sphingosine backbone – 18 carbon amino • alcohol backboneis the third major component o
Cholesterol 18 Carbon
Sphingolipid biosynthesis membranes
-‐ Important in nerve tissue cell membranes – Most common steroid in animals
Sphingolipid Biosynthesis
-‐ Genetic defects in DL metabolism à many disease
– Precursor for all other animal steroids
-‐ Sphingomyelin highly abundant in nervous system
H3C
CH3
CH3
Cholesterol
Sphingosine Ceramide
Cholesterol
(85% of all SL) Properties & Function
Sphingomyelin* HO
*Important in nerve tissue cell membranes
Cholesterol
third major• component
Cholesterol is amphipathic OH
Genetic defects inisSL
-‐ Cholesterol themetabolism # many diseases
of membranes
28!
o Most common steroid in – animals
Small hydrophilic OH head group
o Precursor for all other animal steroids
– Rigid and planar CH3
Cholesterol properties and function
-‐ Cholesterol is amphipathic
o Small hydrophilic OH• head
Modulates
group membrane fluidity
CH3
o Rigid and planar – Disrupts packing of hydrocarbon tails
-‐ Modulates membrane fluidity
– Slows motion of hydrocarbon tails
o Disrupts packing of hydrocarbon tails
CH3
o Slows motion of hydrocarbon tails
Lipid distribution is membrane specific
30!
-‐ Has a lot to do with the function
Lecture 1 – Lipid Structure & Properties
Why are membranes important?
-‐ Protection
-‐ Selectively permeable (No nutrition in, no O2 in, no waste out – all permeable not good either)
-‐ Specialization
-‐ Compartmentalize genetic material so it stays distinct
Lecture 1 Overview – Lipid structure and properties
-‐ Review structure and properties of fatty acids
-‐ Review structure and properties of the most common lipid found in membranes
o Glycerophospholipids
o Sphingolipids
o Cholesterol
-‐ Describe the role of lipids in health and disease
Biological Lipids!
Biological lipids
LIPIDS
Fatty Acids Steroids
Waxes Eicosanoids Triglycerides
Glycerophospholipids* Sphingolipids* Cholesterol*
* Primary lipids in biological membranes
-‐ Fatty acids is a much more diverse family
*Primary lipids in biological membranes
6!
General properties of lipids
-‐ Solubility
o Low in water and high in non-polar solvents
-‐ Hydrophobic and/or amphipathic
o Contain both polar and non-polar groups Saturated Fatty Acid Structure!
-‐ Self-assemble in water
Polar
o Hydrophobic effect and van der Waals interactions Non-polar Carboxylic
Hydrocarbon tail acid
Saturated fatty acid structure H H H H H H H H H H H H H H H O
=
H!C!C!C!C!C!C!C!C!C!C!C!C!C!C!C!C
!
OH
-‐ Alkane adopts lowest energy form based on steric clash H H H H H H H H H H H H H H H
-‐ Physiological pH most acids are deprotonated ∴ makes (CH2)n H H H H H H H H
them more polar H H
H3C
-‐ Extended conformation = zigzag H H
H H H H H H H H
CH3
‘Anti’ conformation Extended conformation
Saturated fatty acid nomenclature
Unsaturated Fatty Acids!
is most stable is most stable 8!
-‐ 4 ways to name a fatty acid but only talk about 3 H H
1. Symbol
Oleic Acid
a. [#C]:[# of double bonds]
b. 18:0 O
2. Systematic name OH
a. Octadecanoic acid
3. Common name
a. Steric acid
• Double bonds almost always in cis conformation
• Results in a kink in structure
10!
,Unsaturated fatty acids
-‐ Double bonds almost always in cis conformation
-‐ Results in a “kink” in structure
Mono-unsaturated fatty acids
-‐ Symbol
o 18:1
-‐ Systematic name
o 9-octadecenoic acid
-‐ Common name
o Oleic acid
Poly-unsaturated fatty acids (PUFAs)
-‐ Symbol
o 18:2
-‐ Systematic name
o 9,12-octadecadienoic acid
-‐ Common name
Packing
o Linoleicofacid
Fatty Acids
Packing of fatty acids
Fatty Acid Properties!
3 stearate 2 stearate + 1 oleate Carbons: Common Melting
-‐ Disrupted packing in 2 stearate + 1 oleae double bonds Name point
13! C16:0 Palmitate 63 °C
Fatty acid properties
C18:0 Stearate 70 °C
-‐ Understand and know that an introduction of a double bond
can cause significant decrease in melting point C16:1 Palmitoleate -0.5 °C
-‐ Melting point reflects how stable the structure is C18:1 Oleate 13 °C
C18:2 Linoleate -9.0 °C
Fatty acids in health and disease
-‐ Fatty acid intake impacts cardiovascular health 14!
Partial Hydrogenation!
o Saturated fatty acids =↑ disease
o Unsaturated fatty acids =↓ disease Melting Temp
O
-‐ Not all unsaturated fatty acids are good
OH
o Hydrogenation of unsaturated fats during food -9°C
Vegetable Oil
processing produces unhealthy fatty acids Healthy but impractical for (fast) food industry
Partial hydrogenation “Partial Hydrogenation”
-‐ Vegetable oil H2 (limiting)
o Healthy but impractical for (fast) food industry O
45°C
o Melting temperature -9°C OH
-‐ Elaidic acid – trans fatty acid Elaidic Acid – Trans Fatty Acid
o Good for baking and long shelf life but Great for baking + long shelf-life but unhealthy
*worse than saturated fatty acids*
unhealthy 16!
, o Worse than saturated fatty acids
o Melting temperature 45°C
-‐ Converting vegetable oil into elaidic acid by partial hydrogenation limiting H2 goes from a cis bond to a
trans dramatically increases the melting temperature
Some Fatty Acids are Essential!
Some fatty acids are essential
• Required forfor
-‐ Required normal
normalhealth butcannot
health but cannot
be be made
made
– We cannot
o Wesynthesize doubledouble
cannot synthesize bonds pastpast
bonds C9*C9*
o Thus, must acquire from diet O
-‐ Animals
• Animals need
need twoEFAs
two EFAsfrom
from diet
diet: Fish Oil
HO
!-Linolenic acid (18:3 "3)
3
O
Eicosapentaenoic acid (20:5 "3)
"-Linolenic Acid = Omega-3 Fatty Acid 3
HO
O O
Docosahexanoic acid (22:6 "3)
* !2
HO 3
-O
!3 ! - anti-inflammatory
Linoleic Acid = Omega-6 Fatty Acid
O
Linoleic acid (18:2 !6)
O Vegetable Oil
!6 6
*
HO
O
-O Arachidonic acid (20:4 !6)
! 17! 6
HO
- pro-inflammatory
Fatty acids are the “tails” of membrane lipids
-‐ In membranes fatty acids are attached to
A healthy diet has a balance of ω3 to ω6 18!
phosphate containing head group
1. Glycerophospholipids
Glycerophospholipids
2. Sphingolipids
General Structure!
Glycerophospholipids general structure
Glycerophospholipids
Headgroup
• Glycerophospholipids are the most
abundant membrane lipids in cells 20!
Glycerophospholipids
Glycerophospholipids
– Based on structure of glycerol
-‐ Glycerophospholipids are the most abundant membrane lipids in cells
o Based on structure of glycerol Fatty Acyl Chains
HO HO Glycerol backbone
CH2 CH2
HO C H HO C H O
H2C OH H2C O P O-
O-
Glycerol Glycerol-3-Phosphate
21!
Glycerophospholipid properties Phosphate Head Group
-‐ Constant
o Glycerol & phosphate 22!
-‐ Variable
, o Fatty acid tails (length, degree of unsaturation)
o Head groups (size, charge)
Neutral Glycerophospholipids Anionic Glycerophospholipids
Neutral glycerophospholipids Anionic Glycerophospholipids
-1 +1
Sphing
-1 +1
• Sphingolipids are the
of membrane lipids
– Based on structure of s
PC and PE are zwitterionic (net neutral) 25!
26!
Sphingolipids Cholesterol
-‐ Sphingolipids are the second major class of membrane lipids
o Based on structure of sphingosine (not glycerol)
Sphi
o Sphingosine backbone – 18 carbon amino • alcohol backboneis the third major component o
Cholesterol 18 Carbon
Sphingolipid biosynthesis membranes
-‐ Important in nerve tissue cell membranes – Most common steroid in animals
Sphingolipid Biosynthesis
-‐ Genetic defects in DL metabolism à many disease
– Precursor for all other animal steroids
-‐ Sphingomyelin highly abundant in nervous system
H3C
CH3
CH3
Cholesterol
Sphingosine Ceramide
Cholesterol
(85% of all SL) Properties & Function
Sphingomyelin* HO
*Important in nerve tissue cell membranes
Cholesterol
third major• component
Cholesterol is amphipathic OH
Genetic defects inisSL
-‐ Cholesterol themetabolism # many diseases
of membranes
28!
o Most common steroid in – animals
Small hydrophilic OH head group
o Precursor for all other animal steroids
– Rigid and planar CH3
Cholesterol properties and function
-‐ Cholesterol is amphipathic
o Small hydrophilic OH• head
Modulates
group membrane fluidity
CH3
o Rigid and planar – Disrupts packing of hydrocarbon tails
-‐ Modulates membrane fluidity
– Slows motion of hydrocarbon tails
o Disrupts packing of hydrocarbon tails
CH3
o Slows motion of hydrocarbon tails
Lipid distribution is membrane specific
30!
-‐ Has a lot to do with the function
