1. BIOCHEMISTRY Lipids of physiological significane (Harper)

2. Lipids
Lipids: a heterogeneous class of naturally occurring organic compounds (mainly esters) classified together on the basis of common solubility properties

3. Lipids Lipids include ESTERS (of fatty acid with alcohol)
Triacylglycerols (triglycerides), phosphoacylglycerols (phospholipids), sphingolipids, glycolipids.
NON-ESTERS
cholesterol, steroid hormones, and bile acids
lipid-soluble vitamins, and prostaglandins

4. an organic compound made by replacing the hydrogen of an acid by an alkyl or other organic group.

5. ESTER
an organic compound made by replacing the hydrogen of an acid by an alkyl or other organic group. Many naturally occurring fats and essential oils are esters of fatty acids.

9. Waxes Waxes are very water insoluble and high melting point.
They are widely distributed in nature as protective waterproof coatings on leaves, fruits, animal skin, fur, feathers and exoskeletons
Prentice Hall c2002
Chapter 9

10. Waxes
Esters of long-chain fatty acids and long chain monohydroxylic alcohols
from the Old English word weax = honeycomb

11. Triacylglycerols Esters of glycerol with three fatty acids
Fatty acids are stored as neutral lipids, triaclyglycerols (TGs)
TGs are hydrophobic, stored in fat cells (adipocytes)
Structure of a triacylglycerol
Prentice Hall c2002
Chapter 9

12. Structures of glycerophospholipids
Phosphatidylcholine (PC)
Prentice Hall c2002
Chapter 9

13. Structures of glycerophospholipids

14. Structures of glycerophospholipids
Phosphatidylserine (PS)
Prentice Hall c2002
Chapter 9

15. Cardiolipin:
Two molecules of PA esterified through their phosphate groups to an additional molecule of glycerol is called cardiolipin

16. Importance of cardiolipin
Cardiolipin is found in bacteria and eukaryotes (inner mitochondrial membrane)
Cardiolipin is antigenic, and is recognized by antibodies raised against Treponema pallidum, the bacterium that causes syphilis
Anticardiolipin antibody test

17. Sphingolipids
Sphingolipids - sphingosine is the backbone. Abundant in central nervous system tissues
Ceramides - fatty acyl group linked to sphingosine
Sphingomyelins - phosphocholine attached to ceramide
Cerebrosides - glycosphingolipids with one monosaccharide residue attached to ceramide
Galactosylcerebrosides - a single b-D-galactose as a polar head group
Gangliosides - contain oligosaccharide chains with N-acetyl-neuraminic acid (NeuNAc) attached to a ceramide
Prentice Hall c2002
Chapter 9

18. Sphingolipids (backbone is Sphingosine)
Ceramide is the parent compound for spingolipid.
Amino alcohol (sphingosine)
Fatty acid

19. Sphingosine (b) Ceramides
Prentice Hall c2002
Chapter 9

20. Ceramide
A long-chain fatty acid is attached to the amino group of sphingosine through an amide linkage

21. Sphingomyelin Amino alcohol sphingosine, rather than glycerol
The alcohol group at carbon 1 of sphingosine is esterified to phosphorylcholine
Sphingomyelin is an important constituent of the myelin of nerve fibers

22. Sphingomyelin degradation
Sphingomyelin is degraded in lysosomes by sphingomyelinase to give ceramide,
and ceramidase to give sphingosine
Niemann-Pick disease is due to sphingomyelinase deficiency

23. Glycolipids Also known as glycosphingolipids
contain both carbohydrate and lipid components
Ceramides plus a long-chain fatty acid attached to the amino alcohol sphingosine
essential components of:
All membranes
Nerve cells

24. Glycolipids Significance
Glycosphingolipids are antigenic  a source of blood group antigens
The carbohydrate portion of a glycolipid is the antigenic determinant
serve as cell surface receptors for cholera and tetanus toxins

25. Galactocerebroside—the most common cerebroside found in membranes
Structure of a galactocerebroside
Galactocerebroside—the most common cerebroside found in membranes
Glucocerebroside
Prentice Hall c2002
Chapter 9

26. Location
cerebrosides predominantly in the brain and peripheral nervous tissue

27. Ganglioside (sphingolipid)
found in the ganglion cells
Derivatives of ceramide oligosaccharides, and contain one or more molecules of NANA.
negatively charged at physiologic pH  provided by N-acetylneuraminic acid (NANA).
[NANA is also referred to as sialic acid.]