Glycolipids are essential components of cell membranes and are most abundant in nervous tissues. They do not contain phosphate. The main types of glycolipids are cerebrosides, sulfatides, globosides, and gangliosides. Cerebrosides contain a ceramide bonded to a monosaccharide and are highly concentrated in the white matter of the brain and myelin sheaths of nerves. Gangliosides contain ceramide bonded to oligosaccharides and sialic acid and are present in high amounts in the brain. Glycolipids are involved in cell receptor functions, cell interactions, and mediating cell-cell recognition. Defects in glycolipid metabolism can cause various storage diseases.

1. GLYCOLIPIDS
By
N. Santhosh Kumar
Asst. Professor
Department Of Biochemistry
SIMS & RH
Tumkur

2. • Glycolipids they do not contain phosphate.
• Essential components of cell or plasma membranes (outer leaflet) &
also most abundant in nervous tissues
Glycolipids
Cerebrosides
Sulfatides
Globosides
Gangliosides
Ceramide Carbohydrate
Glycolipids

3. CEREBROSIDES
• High conc in white matter of brain & Myelin sheaths of nerves.
• 4 types, differing only with respect to the type of fatty acids
Monosaccharides
Types of cerebrosides Fatty acid
Kerasine Lignoceric acid
Cerebron Cerebronic acid
Nervon Nervonic acid
Oxynervon Hydroxy derivatives of Nervonic acid

4.  Simplest glycolipids –
 Glucocerebrosides (Ceramide + Glucose) – Extra neural (non-
neural) tissues.
• Galactocerebrosides(Ceramide + Galactose) -Nerve tissue
membrane.
• It provide protective coating to each nerve and act as insulator

5. GLOBOSIDES
• Sugars are usually a combination of D- glucose , D-
galactose or N-acetyl galactosamine.
Ceramide

6. SULFATIDES
• It is widely distributed in plants.
• Found in chloroplast & chromatophores of photosynthetic
bacteria.
• Most common sulfatide is Sulfogalactoceramide, which is found in
nerve tissue.
Ceramide + Monosaccharides + Sulfate

7. GANGLIOSIDES
• Imp Gangliosides present in the brain - GM1, GM2, GM3, GD & GT.
• (G – Gangliosides, While, M- mono, D- di & T- tri sialic acid
residues & number denotes the migration in chromatography or
electrophoresis).
• Simplest Gangliosides found in tissue is GM3
Ceramide + Oligosaccharides + N–acetyl neuraminic acid

8. Functions of Glycolipids
Involved in cell membrane receptors for certain
polypeptide hormones
Cell interactions, growth &
development
Antigenic property
(e.g., blood group antigens)
Act as surface receptors for some toxins &
viruses
Mediating cell-cell recognition

9. Sphingolipid storage diseases (sphingolipidoses)
Sphinogolipidoses Defective enzyme Accumulated
substrate
Clinical features
Niemann-pick
disease
Sphingomyelinase Sphingomyelin
(brain, liver & spleen)
Hepatosplenomegaly, mental
retardation
Tay-sach’s
disease
Hexosaminidase Ganglioside -
GM2 (brain)
Mental retardation, blindness,
cherry red spot on macula,
muscle weakness
Gaucher’s
disease
Gluco
cerebrosidase
Gluco
cerebrosides
( R.E cells. i.e., liver,
spleen, bone marrow)
Hepatosplenomegaly, weight
loss, mental retardation
Krabbe’s
disease
Galacto
cerebrosidase
Galacto
cerebrosides
Absence of myelin leading to
mental retardation
Metachromatic
leukodystrophy
Sulphatidase Sulphatides mental retardation,Psychological
disturbances in adults

10. LIPOPROTEINS

11. Protein
Lipid
Apoprotein
Lipoprotein
•Lipoproteins composed of triglyceride and cholesterol ester core & surrounded by
single lipid layer containing phospholipid and free cholesterol & a shell of proteins.

12. CLASSIFICATION
According to their physical & chemical properties
Based on the density:
Separated by ultracentrifugation into 4 types
• Chylomicrons
• Very low density lipoproteins (VLDL)
• Low density lipoproteins (LDL) & IDL
• High density lipoproteins (HDL) – HDL-1, 2 & 3

13. Based on the electrophoretic mobility
In origin – chylomicrons
Migrating into β-globulin region – β-lipoprotein (LDL)
pre-β-globulin region –pre -β-lipoprotein (VLDL)
α-globulin region – α-lipoproteins (HDL)

14. Lipoprotein class Density (g/mL) Diameter
(nm)
Protein % Phospholipid % TG %
Chylomicrons < 0.95 100 - 500 1 – 2 7 84
VLDL 0.95 – 1.006 30 - 80 10 18 50
LDL 1.019 – 1.063 18 – 28 25 21 4
IDL 1.006-1.019 25 - 50 18 22 31
HDL 1.063-1.21 5 – 15 33 29 8
Composition lipoproteins

15. Families Chylomicrons LDL VLDL HDL
Lp-A A-I & II ---- ---- A-I & II
Lp-B Apo-B48 Apo-B48 Apo-B100 ---
Lp-C C-I, II, III C-I, II III C-I, II, III C-I, II, III
Lp-D --- -- -- HDL -3
Lp-E Apo-E Apo-E Apo-E Apo-E
Apolipoproteins
Major protein components of lipoproteins - Apo-proteins
These are classified by (A, B, C, D & E)
Sub groups given in roman numeral depending on the emerge
from a chromatographic column.

16. Apoprotein Functions
A-I In plasma; activates LCAT
A-II Enhances hepatic lipase activity
B-48 & B-100 Binds to LDL receptor
C-I Activate LCAT
C-II Activates lipoprotein lipase
C-III Inhibits lipoprotein lipase
D Also called as cholesterol ester transfer protein (CETP)
E Binds to LDL receptor

17. Functions of Apo-lipoprotein:
• Maintaining the structural integrity of the lipoproteins
• Responsible for recognition of particle by receptors
• Regulating certain enzymes, which act on the lipoproteins

18. FUNCTIONS OF LIPOPROTEINS
Chylomicron:
Transport of dietary triglyceride and cholesterol esters
from intestine to peripheral tissues and liver.
Very low density lipoprotein (VLDL):
Transports endogenous triglyceride from liver to
peripheral tissues.

19. LDL:
• It transports cholesterol from the liver to the peripheral
tissues, for use to form steroid hormones and building cell
membranes.
• But it also favors the deposition of cholesterol in arterial
walls and thus appears to play a role in disease of the blood
vessels and heart.
• It increased risk for myocardial infarction - Bad cholesterol

20. HDL:
• It transports free cholesterol from the peripheral tissue to the
liver, for using in energy metabolism, membrane
reconstruction and hormone function.
• HDLs also appear to prevent cholesterol from invading and
settling in the walls of arteries.
• It is an anti atherogenic agent.- Good Cholesterol

21. Next PPT
CL-05 Steorids