Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Chapter 8
Lipidsto accompany
Biochemistry, 2/eby
Reginald Garrett and Charles Grisham
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Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Outline
• 8.1 Fatty Acids• 8.2 Triacylglycerols• 8.3 Glycerophospholipids• 8.4 Sphingolipids• 8.5 Waxes• 8.6 Terpenes• 8.7 Steroids
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Classes of Lipids
All biological lipids are amphipathic • Fatty acids • Triacylglycerols • Glycerophospholipids • Sphingolipids • Waxes • Isoprene-based lipids (including steroids)
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
8.1 Fatty acidsKnow the common names and structures
for fatty acids up to 20 carbons long • Saturated
– Lauric acid (12 C) – Myristic acid (14 C) – Palmitic acid (16 C) – Stearic acid (18 C) – Arachidic acid (20 C)
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Fatty acids - II
• Unsaturated fatty acids – Palmitoleic acid (16:1) – Oleic acid (18:1) – Linoleic acid (18:2) -Linolenic acid (18:3) -Linolenic acid (18:3) – Arachidonic acid (20:4)
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Fatty acids - III
Structural consequences of unsaturation • Saturated 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
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
8.2 Triacylglycerols
Also called triglycerides • A major energy source for many
organisms • Why?
– Most reduced form of carbon in nature – No solvation needed – Efficient packing
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Triacylglycerols - II
Other advantages accrue to users of triacylglycerols
• Insulation • Energy without nitrogen • Metabolic water
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
8.3 Glycerophospholipids
Glycerophospholipids are phospholipids but not necessarily vice versa
• Know the names and structures in Figure 8.6
• Understand the prochirality of glycerol • Remember that, if phospholipid contains
unsaturation, it is at the 2-position
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Ether Glycerophospholipids
An ether instead of an acyl group at C-1 • See Figure 8.8 • Plasmalogens are ether
glycerophospholipids in which the alkyl chain is unsaturated
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
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
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
8.4 SphingolipidsBase structure is sphingosine
• Sphingosine is an 18-carbon amino alcohol
• Ceramides are amide linkages of fatty acids to the nitrogen of sphingosine
• Glycosphingolipids are ceramides with one or more sugars in beta-glycosidic linkage at the 1-hydroxyl group
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
8.4 Sphingolipids
• Glycosphingolipids with one sugar are cerebrosides
• Gangliosides - ceramides with 3 or more sugars, one of which is a sialic acid
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
8.5 Waxes
Esters of long-chain alcohols with long-chain fatty acids
• Highly insoluble • Animal skin and fur are wax-coated • Leaves of many plants • Bird feathers
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
8.6 Terpenes
Based on the isoprene structure • Know nomenclature • Understand linkage modes (Figure 8.16) • See structures in Figure 8.17 • All sterols (including cholesterol) are
terpene-based molecules • Steroid hormones are terpene-based
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
8.7 Steroids
• Based on a core structure consisting of three 6-membered rings and one 5-membered ring, all fused together
• Cholesterol is the most common steroid in animals and precursor for all other steroids in animals
• Steroid hormones serve many functions in animals - including salt balance, metabolic function and sexual function
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company
Biochemistry 2/e - Garrett & Grisham
Copyright © 1999 by Harcourt Brace & Company