Collagen is the most abundant protein in your body. It is the major component of connective tissues that make up several body parts, including tendons, ligaments, skin and muscles (1). Collagen has many important functions, including providing your skin with structure and strengthening your bones (

1. Collagen
Prepared by :
LEZAN IBRAHIM

2. • Most abundant protein in body (25-30% of all
protein)
• >20 distinct forms
• Types I, III, IV, V, VI, VIII most common in CV
system
• Types I, III form fibres –major structural elements
• synthesized by fibroblasts and SMCs
• Type IV forms a porous network (basement
membrane) for endothelial cells to attach to
(synthesized by ECs)
• Types V, VI: provides thin covering over SMCs
Collagen

3. • Fibres are folded at physiologic loads
• Half-life in CV system on order of 15-90 days
• Degraded by blood borne enzymes
- Proteases (matrix metalloproteinases, MMPs)
- released by macrophages
• De-natured by heat (approx 60°C)
Collagen

4. Collagen Fibre Assembly
Collagen fibril
10-500 nm
Collagen fibre
1-500m
Stabilised by cross links
AssemblyAssembly
Procollagen
peptidase
Chains
assemble
Precursor 
chain
Procollagen
(triple helix
with loose ends)
Collagen
molecule
67 nm
Intracellular
1 2 3 4

5. Hierarchy of structure
Size range
Visualisation
n.b. 1Å = 0.1nm

6. Hierarchy of structure

7. 0.87nm
66nm
Glycine every third residue
Collagen molecule
LH helix
RH helix

8. Type I
Type II
Type III
disulphide bonds

9. Collagen aggregate structure
Fibre forming
(Types I,II,III,V,K)
Membranous
(Type IV)

10. Stagger of collagen molecules in a
fibril
Total length = 4.4D where D is the length of the striation

11. Tendon Skin

12. Ground substance
• Mucopolysaccharides (glycosaminoglycans)
• Water
• Approx 3% of arterial wet weight
• Viscous but not elastic

13. Chondroitin Sulphate
Keratin Sulphate
Hyaluronate
Proteoglycans
Proteoglycans
– Proteins with covalently bound glycosaminoglycans
(linear polymers with disaccharide units) along length
– Can hold 50x their dry weight in water
– Resistant to compression due to high water content

14. Fibronectin
• Glycoprotein synthesized by fibroblasts, SMCs, ECs
• Mediates cellular interactions and migrations (e.g.
guides macrophages into wound areas)
• Binds fibroblasts to collagen substrates
• Crosslinks and stabilizes other components of ECM -
• patterns of FN similar to patterns of microfilaments
50m

15. Laminin
10m
• Found primarily in the basal laminae-
specialized thin (50 nm) sheets of ECM
material separating endothelial cells from ECM
• Maintains tissue organization
• Acts as “molecular sieve”

16. Collagen function
Collagen is an important protein that can be found
throughout your body. In fact, it is found in all the
connective tissues in your body ranging from your skin
and bones, all the way down to your organs and blood
vessels. Collagen functions several different ways in
your body.

17. • Skin
One of the most noticeable functions of collagen is the
support it provides for your skin. According to Dr. Eric F.
Bernstein of the University of Pennsylvania School of
Medicine, collagen makes up approximately 80 percent of
the dry weight of your skin. Collagen provides structure to
the skin, and works hand in hand with another protein,
called elastin, to allow skin the flexibility it needs to stretch
and return to its original state as your body moves.

18. • Bone
Collagen also has an important function in bone. Bone is made up of a
mixture of collagen and a mineral called hydroxyapatite. The two work
together to form the structure, flexibility and strength of your bones.
According to research done by the Radiocarbon Laboratory, at the
University of Waikato in New Zealand, approximately 30 percent of
bones are made up of organic materials, of which collagen makes up to
95 percent.
Muscles
Collagen also provides important functions for your muscles. Collagen
fibers provide your muscles with the strength and structure needed to
move and function throughout the day. Collagen fibers not only make up
your skeletal muscle fibers, but they also make up your smooth muscles
(such as those in the bladder and reproductive system) and your cardiac
(heart) muscles.
Blood Vessels
Collagen also provides important function in your blood vessels.
Collagen makes up the walls of the veins, arteries and capillaries of the
body. This gives the vessels strength, structure and flexibility, all of
which are needed to effectively transport blood throughout your entire