what is lipid lipids là gì
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Biochemistry 2/e - Garrett & Grisham
ADVANCED BICHEMICAL ENGINEERING
Chapter 8
Lipids
Nguyen Van Tuyen
Copyright © 1999 by Harcourt Brace & Company
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Biochemistry 2/e - Garrett & Grisham
What is lipid ?
Barriers to more
polar molecules
- low solubility in water >< high solubility in nonpolar solvents
- metabolic energy storage
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Biochemistry 2/e - Garrett & Grisham
Outline
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8.1 Fatty Acids
8.2 Triacylglycerols
8.3 Glycerophospholipids
8.4 Sphingolipids
8.5 Waxes
8.6 Terpenes
8.7 Steroids
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Biochemistry 2/e - Garrett & Grisham
Classes of Lipids
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All biological lipids are amphipathic
Fatty acids
Triacylglycerols
Glycerophospholipids
Sphingolipids
Waxes
Isoprene-based lipids (including steroids)
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Biochemistry 2/e - Garrett & Grisham
8.1 Fatty acids
- Several number of carbon atoms (usually 14 to 24)
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Biochemistry 2/e - Garrett & Grisham
8.1 Fatty acids
• Saturated (all carbon–carbon bonds are single bonds)
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Biochemistry 2/e - Garrett & Grisham
Fatty acids - II
• Unsaturated fatty acids (with one or more double bonds in the
hydrocarbon chain; monounsaturated – polyunsaturated )
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Biochemistry 2/e - Garrett & Grisham
Fatty acids - III
saturation >< unsaturation
- Unsaturated fatty acids are slightly more abundant in nature
than saturated fatty acids, especially in higher plants.
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chains pack tightly and form more rigid,
organized aggregates (i.e., membranes)
- Unsaturated chains bend and pack
in a less ordered way, with greater
potential for motion
Arachidonic acid
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Biochemistry 2/e - Garrett & Grisham
- several other modified fatty acids
a cyclopropane ring
a branched-chain fatty acid
- Some fatty acids are synthesized by mammals’s diet – plant
source (linoleic and γ –linolenic acids,..)
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Biochemistry 2/e - Garrett & Grisham
8.2 Triacylglycerols (triglycerides)
• A major energy source the principal neutral derivatives
of glycerol for many organisms
• Why?
- Most reduced form of carbon in nature yield large
amounts of energy in the oxidative reactions of
metabolism
(1 g of triacylglycerols 38 kJ of energy)
- Their hydrophobic nature allows them to aggregate in
highly anhydrous forms
- Efficient packing
Copyright © 1999 by Harcourt Brace & Company
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Biochemistry 2/e - Garrett & Grisham
8.2 Triacylglycerols (triglycerides)
- Consist of a glycerol esterified with three fatty acids
- soluble in benzene, chloroform, ether, and hot ethanol
Serves as a depot or
storage site for lipids
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Biochemistry 2/e - Garrett & Grisham
Triacylglycerols - II
Other advantages accrue to users of triacylglycerols
• Insulation
Fat is a poor conductor of heat, adipose tissue have highly
triacylglycerol content, cover the body prevent heat loss
• Energy without nitrogen
• Metabolic water - by oxidizing energy-containing
substances
- triacylglycerols are nonpolar anhydrous form <
glycogen
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Biochemistry 2/e - Garrett & Grisham
Triacylglycerols
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Biochemistry 2/e - Garrett & Grisham
Phospholipids
• major component of all cell
membranes
• amphiphilic characteristic
lipid bilayers
• 2 types of phospholipids:
phosphoglycerides and
sphingomyelins
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Biochemistry 2/e - Garrett & Grisham
8.3 Glycerophospholipids
Glycerophospholipids are phospholipids but not
necessarily vice versa
• if phospholipid contains unsaturation, it is at the 2position
• The most numerous phospholipid moleculers foung
in cell membranes
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Biochemistry 2/e - Garrett & Grisham
8.3 Glycerophospholipids
Glycerophospholipids are phospholipids but not
necessarily vice versa
• the prochirality of glycerol
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Biochemistry 2/e - Garrett & Grisham
Most Common Phospholipid
head
- Important intermediate in the biosynthesis
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Biochemistry 2/e - Garrett & Grisham
most common
constituents of
biological membranes
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Heart
tissue
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Biochemistry 2/e - Garrett & Grisham
- The nature of the fatty acids
can greatly affect the chemical and physical
properties of the phosphatides and
the membranes that contain them
A space-filling model of
1-stearoyl-2-oleoyl-phosphatidylcholine.
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Biochemistry 2/e - Garrett & Grisham
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Biochemistry 2/e - Garrett & Grisham
Glycerophospholipid Degradation: One of the Effects of Snake Venoms
Phospholipases - enzymes that cause the breakdown of
phospholipids.
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Biochemistry 2/e - Garrett & Grisham
Ether Glycerophospholipids
An ether instead of an acyl group at C-1
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Biochemistry 2/e - Garrett & Grisham
Ether Glycerophospholipids
• Platelet activating factor
(PAF) is an ether
glycerophospholipid
• PAF is a potent
biochemical signal
molecule
• Note the short (acetate)
fatty acyl chain at the C-2
position in PAF more
water-soluble soluble
messenger in signal
transduction
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Biochemistry 2/e - Garrett & Grisham
Plasmalogens
• the alkyl moiety
is cis-α,βunsaturated
• head groups
include choline,
ethanolamine,
and serine
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Biochemistry 2/e - Garrett & Grisham
8.4 Sphingolipids
Base structure is sphingosine
• Sphingosine is an 18carbon amino alcohol
• Ceramides are amide
linkages of fatty acids to
the nitrogen of sphingosine
• Glycosphingolipids are
ceramides with one or
more sugars in betaglycosidic linkage at the 1hydroxyl group
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