The document discusses fibrous proteins and collagen. It provides details on: 1) Fibrous proteins are usually insoluble and found in skin, connective tissue, blood vessels and other structures. They have high alpha-helix or beta-sheet content and examples include collagen, elastin, keratin and fibroin. 2) Collagen is the most abundant fibrous protein, making up 25-35% of the body's protein. It provides structure and strength, and there are at least 19 types designated by Roman numerals. 3) Collagen has a characteristic amino acid sequence of glycine-X-Y where X is often proline and Y can be hydroxyproline or hydroxy

3. OVER VIEW
• THESE ARE BASIC STRUCTURAL ELEMENTS.
• FIBROUS PROTEINS ARE USUALLY INSOLUBLE .
• THEY ARE FOUND AS COMPONENTS OF SKIN, CONNECTIVE
TISSUE, BLOOD VESSELS, SCLERA AND CORNEA OF EYE.

4. OVER VIEW
• FIBROUS PROTEINS HAVE HIGH A-HELIX OR B-SHEET CONTENT.
• EXAMPLES INCLUDE:
COLLAGEN
ELASTIN
KERATIN
FIBROIN

5. COLLAGEN

6. BASIC INFORMATION
Derived from Greek word “kolla” meaning “Glue Producer”
Most abundant Fibrous protein (structural protein) in vertebrates
25% or more(up to 35%) of total body protein
Major component of connective tissue
Provides an extracellular framework for Strength & Flexibility
At least 19 distinct types of Collagen
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7. TYPES OF COLLAGEN
•THE TYPES OF COLLAGEN ARE DESIGNATED BY ROMAN NUMERALS.
•THE COLLAGEN GENES ARE NAMED ACCORDING TO THE COLLAGEN TYPE, WRITTEN IN ARABIC
NUMERALS FOR THE GENE SYMBOL, FOLLOWED BY AN A AND THE NUMBER OF THE PRO Α CHAIN
THAT THEY ENCODE. THUS, THE COL1A1 AND COL1A2 GENES ENCODE THE Α1 AND Α2 CHAINS OF
TYPE I COLLAGEN, RESPECTIVELY.
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9. STRUCTURE OF COLLAGEN
Amino acid
sequence
Triple-helical
structure
Hydroxyproline
and
Hydroxylysine
Glycosylation

10. 1… AMINO ACID SEQUENCE:
 COLLAGEN IS A GLYCOPROTEIN CONTAINING GALACTOSE AND GLUCOSE AS THE
CARBOHYDRATE CONTENT.
 GLYCINE IS ONE - THIRD OF TOTAL AMINO ACID CONTENT OF COLLAGEN
FOLLOWED BY HYDROXYPROLINE AND PROLINE
• GLYCINE IS THE PART OF THE REPEATING SEQUENCE.
GLY- X-Y
• X- IS FREQUENTLY PROLINE
• Y- HYDROXY PROLINE OR HYDROXYLYSINE.

12. 2… TRIPLE- HELICAL STRUCTURE
• AMINO ACIDS SIDE CHAINS ARE ON THE SURFACE OF THE
TRIPLE HELICAL MOLECULE.
• THIS ALLOWS BOND FORMATION BETWEEN THE EXPOSED
R- GROUPS OF NEIGHBORING COLLAGEN MONOMERS-
THIS LEADS TO AGGREGATION INTO FIBRILS.

13. HYDROXYPROLINE & HYDROXYLYSINE:
HYDROXYLATION OF PROLINE & LYSINE RESIDUES AFTER THEIR
INCORPORATION INTO THE POLYPEPTIDE CHAINS.
THUS CALLED POST TRANSLATIONAL MODIFICATION.
CAUSES STABILIZATION OF TRIPLE HELICAL STRUCTURE.

14. 14
Proline
3-Hydroxyproline 4-Hydroxyproline
Glycine

15. NH2
|
NH2 – CH2 – CH – CH2 – CH2 - C – H
|
COOH
15
Lysine
5-Hydroxylysine

16. GLYCOSYLATION
• HYDROXYL GROUP OF HYDROXYLYSINE RESIDUES OF COLLAGEN ARE
ENZYMATICALLY GLYCOSYLATED.
• MOST COMMONLY GLUCOSE AND GALACTOSE ARE ATTACHED.

18. BIOSYNTHESIS OF COLLAGEN
PRECURSORS:
COLLAGEN IS ONE OF THE PROTEINS THAT FUNCTIONS OUTSIDE
THE CELL.
POLYPEPTIDE PRECURSORS OF THE COLLAGEN MOLECULE ARE
FORMED IN FIBROBLAST, OSTEOBLASTS AND CHONDROBLASTS.
THESE ARE SECRETED INTO THE EXTRACELLULAR MATRIX.

19. Formation of Pro- α-
chains
Hydroxylation
Glycosylation
Assembly and
Secretion
Extracellular cleavage
of Procollagen
molecules
Formation of
collagen fibrils
Cross-link
formation

21. 21
Glucosyl & Galactosyl added
by glycosyl transfarase &
galactosyl transfarase.

22. 22

23. 23

24. Synthesis Of Collagen

25. USES OF COLLAGEN
• HISTORY:-
• FROM THE GREEK FOR GLUE, KOLLA, THE WORD COLLAGEN MEANS
"GLUE PRODUCER".
• COLLAGEN ADHESIVE WAS USED BY EGYPTIANS ABOUT 4,000 YEARS
AGO, AND NATIVE AMERICANS USED IT IN BOWS ABOUT 1,500 YEARS
AGO. THE OLDEST GLUE IN THE WORLD, CARBON-DATED AS MORE
THAN 8,000 YEARS OLD, WAS FOUND TO BE COLLAGEN — USED AS A
PROTECTIVE LINING ON ROPE BASKETS AND EMBROIDERED FABRICS,
AND TO HOLD UTENSILS TOGETHER; ALSO IN CRISSCROSS
DECORATIONS ON HUMAN SKULLS.

26. INDUSTRIAL USES
• IF COLLAGEN IS PARTIALLY HYDROLYZED, THE THREE TROPOCOLLAGEN
STRANDS SEPARATE INTO GLOBULAR, RANDOM COILS, PRODUCING
GELATIN, WHICH IS USED IN MANY FOODS, INCLUDING FLAVORED GELATIN
DESSERTS. BESIDES FOOD, GELATIN HAS BEEN USED IN PHARMACEUTICAL,
COSMETIC, AND PHOTOGRAPHY INDUSTRIES.
• ANIMAL GLUES ARE THERMOPLASTIC, SOFTENING AGAIN UPON REHEATING,
AND SO THEY ARE STILL USED IN MAKING MUSICAL INSTRUMENTS SUCH AS
FINE VIOLINS AND GUITARS.
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27. MEDICAL USES:-
• COLLAGENS ARE WIDELY EMPLOYED IN THE
CONSTRUCTION OF ARTIFICIAL SKIN
SUBSTITUTES USED IN THE MANAGEMENT
OF SEVERE BURNS & BEAUTY TREATMENTS.
• (THESE COLLAGENS MAY BE DERIVED FROM
BOVINE, PORCINE, AND EVEN HUMAN
SOURCES AND ARE SOMETIMES USED IN
COMBINATION WITH SILICONES,
GLYCOSAMINOGLYCANS, FIBROBLASTS,
GROWTH FACTORS AND OTHER
SUBSTANCES)
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28. • COLLAGEN IS ALSO SOLD COMMERCIALLY AS A JOINT MOBILITY SUPPLEMENT.
• COLLAGEN IS NOW BEING USED AS A MAIN INGREDIENT FOR SOME COSMETIC
MAKEUP.
• RECENTLY AN ALTERNATIVE TO ANIMAL-DERIVED COLLAGEN HAS BECOME
AVAILABLE. ALTHOUGH EXPENSIVE, THIS HUMAN COLLAGEN, DERIVED FROM
DONOR CADAVERS, PLACENTAS AND ABORTED FETUSES, MAY MINIMIZE THE
POSSIBILITY OF IMMUNE REACTIONS.
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29. COLLAGEN IN WOUND HEALING
• VITAL ROLE IN HEMOSTASIS
• ATTRACTS THROMBOCYTES
• ACTIVATES THROMBOCYTES TO SECRETE SEROTONIN,
ADP AND THROMBOXANE A2
• PLATELET PLUG IS FORMED
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30. CHANGES IN COLLAGEN DUE TO AGEING
• INCREASE IN PYRIDINOLINE AND DEOXYPYRIDINOLINE
• INCREASE IN THE THICKNESS OF COLLAGEN FIBER
• INCREASE IN LENGTH
3
0
CHARACTERISTICS
 HAIR WHITENING
 WRINKLING AND TOUGHENING OF NAILS
 WRINKLING AND TOUGHENING OF SKIN

31. ABNORMALITIES ASSOCIATED WITH COLLAGEN
•EHLERS-DANLOS SYNDROME
- GROUP OF INHERITED DISEASE
- COLLAGEN INVOLVED III-
CHARACTERISTICS
- HYPER EXTENSIBILITY OF SKIN.
- ABNORMAL TISSUE FRAGILITY
-INCREASE JOINT MOBILITY
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32. OSTEOGENESIS IMPERFECTA
CAUSED DUE TO ABNORMAL (LESS) COLLAGEN TYPE I
CHARACTERISTICS
- WEAK BONES
- FRAGILE BONES
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33. EPIDERMOLYSIS BULLOSA
DUE TO ALTERATION OF COLLAGEN TYPE VII
CHARACTERISTICS
- SKIN BREAKS
- BLISTER FORMATION
3
3

34. SCURVY
• GLY –X- Y (Y = 4-HYDROXYPROLINE)
• ENZYME : PROPYL-4-HYDROXYLASE
CO-FACTOR: VIT. C. DUE TO VIT C DEFICIENCY
(IMPAIRED SYNTHESIS OF COLLAGEN DUE TO
DEFICIENCIES OF PROLYL AND LYSYL HYDROXYLASES)
CHARACTERISTICS-
- BLEEDING GUM
- DELAYED WOUND HEALING
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35. GENETIC DISEASES DUE TO COLLAGEN
SYNTHESIS ABNORMALITIES-DUE TO GENE
MUTATION
Gene or Enzyme Disease
COL1A1,COL1A2 Osteogenesis imperfecta,
osteoporosis, ehlers-danlos
syndrome type VII
COL2A1 Severe chondrodysplasia
osteoarthritis
COL3A1 Ehlers-danlos syndrome type IV
COL4A3-COL4A6 Alport syndrome (including both
autosomal and X-linked forms)

36. COL7A1 Epidermolysis bullosa, dystrophic
COL10A1 Schmid metaphysial
chondrodysplysia
Lysyl
hydroxylase
Ehlers-danlos syndrome type VI
Propcollagen N-
proteinase
Ehlers-danlos syndrome type VII
autosomal recessive
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37. Fibrous vs. Globular Proteins
1. Compact protein structure Extended protein structure
2. Soluble in water (or in lipid Insoluble in water (or in lipid
bilayers) bilayers)
3. Secondary structure is complex Secondary structure is simple
with a mixture of a-helix, b-sheet based on one type only
and loop structures
4. Quaternary structure is held Quaternary structure is usually
together by noncovalent forces held together by covalent bridges
5. Functions in all aspects of Functions in structure of the body
metabolism (enzymes, transport, or cell (tendons, bones, muscle,
immune protection, hormones, etc). ligaments, hair, skin)
Globular Fibrous

38. • A PROTEIN IS IN ITS NATIVE CONFORMATION WHEN
1. IT IS THERMODYNAMICALLY LEAST STABLE.
2. IT HAS THE HIGHEST GIBBS FREE ENERGY.
3. IT IS IN ANY OF ITS FUNCTIONAL, FOLDED STATES.
4. IT IS UNFOLDED
• HYDROGEN BONDS BETWEEN AMINO ACIDS IN A POLYPEPTIDE OCCUR BETWEEN WHICH CHEMICAL
GROUPS?
1. THE C=O AND C-H GROUPS
2. THE C=O AND C-R GROUPS
3. THE C=O GROUPS
4. THE C-R AND C-R GROUPS
Ans: 3
Ans: 1

39. • PROLINE RESIDUES ARE MOST LIKELY TO OCCUR IN WHICH OF THE FOLLOWING SECONDARY
STRUCTURES?
1. AN Α HELIX
2. A Β TURN
3. A Β SHEET
4. A COILED COIL
• FIBROUS PROTEINS DIFFER FROM GLOBULAR PROTEINS IN THE:
1. FIBROUS PROTEINS TEND TO SERVE STRUCTURAL FUNCTIONS, AND GLOBULAR PROTEINS ARE
MORE LIKELY TO BE ENZYMES
2. FIBROUS PROTEINS CAN OFTEN CONTAIN SEVERAL TYPES OF SECONDARY STRUCTURE, WHEREAS
GLOBULAR PROTEINS USUALLY CONSIST LARGELY OF A SINGLE TYPE OF SECONDARY STRUCTURE
3. GLOBULAR PROTEINS ARE INSOLUBLE IN WATER, AND FIBROUS PROTEINS ARE USUALLY SOLUBLE
4. GLOBULAR PROTEINS ARE MORE LIKELY THAN FIBROUS PROTEINS TO HAVE AN ELABORATE
QUATERNARY STRUCTURE
Ans: 2
Ans: 1

40. • WHY IS THE Α-HELIX CONFORMATION IN POLYPEPTIDES SUCH A STABLE FORM?
1.THE Α HELIX STRUCTURE IS STABILIZED BY HYDROPHOBIC INTERACTIONS
2.THE Α HELIX STRUCTURE IS STABILIZED BY HYDROGEN BONDS
3.THE Α HELIX STRUCTURE IS STABILIZED BY DISULFIDE BONDS
4.THE Α HELIX STRUCTURE IS STABILIZED BY PROLINE RESIDUES
• A PROTEIN IN SOLUTION IS MORE LIKELY TO MAINTAIN ITS NATIVE CONFORMATION
WHEN
1.THE NUMBER OF HYDROGEN BONDS WITHIN A PROTEIN IS MINIMIZED
2.THE NUMBER OF HYDROGEN BONDS WITH WATER MOLECULES IS MAXIMIZED
3.THE PROTEIN IS LEAST STABLE
4.ITS HYDROPHOBIC RESIDUES ARE LARGELY BURIED IN THE PROTEIN INTERIOR
Ans: 4
Ans: 2

41. • WHICH BONDS ARE PLANAR (CANNOT ROTATE) IN A POLYPEPTIDE BACKBONE?
1.CΑ-C BONDS
2.C-N BONDS
3.N-CΑ BONDS
4.CΑ-CΑ BONDS
• IF HELICAL RISE PER AMINO ACID IS 1.5 Å AND LENGTH OF POLYPEPTIDE IS 20 Å, THEN
HOW MANY AMINO ACIDS ARE PRESENT IN THE Α-HELIX?
1.30 AMINO ACIDS
2.17 AMINO ACIDS
3.13 AMINO ACIDS
4.9 AMINO ACIDS
Ans: 2
Ans: 3

42. • IF THERE ARE 101 AMINO ACIDS, THEN HOW MANY BONDS ARE PRESENT AROUND WHICH
ROTATION CAN OCCUR?
1. 101 BONDS
2. 202 BONDS
3. 303 BONDS
4. 505 BONDS
• WHICH IS THE REPEATING UNIT IN COLLAGEN?
1. GLY-X-PRO
2. PRO-GLY-X
3. X-PRO-GLY
4. ALL OF THE ABOVE
5. NONE OF THE ABOVE
Ans: 2
Ans: 4

43. • WHAT IS THE NUMBER OF AMINO ACIDS PER TURN IN Β-SHEETS?
1.1
2.2
3.4
4.NONE OF THESE
• Β-BULGE IS FORMED BECAUSE OF
1.EXTRA AMINO ACID(S) IN LONGER POLYPEPTIDE
2.EXTRA AMINO ACID(S) IN SHORTER POLYPEPTIDE
3.PROLINE IN THE BULGE
4.NONE OF THE ABOVE
Ans: 3
Ans: 1

44. 44