PROTEIN, part of life

1. FIBROUS PROTEIN
PRESENTED BY
SABAHAT ALI
FAIZA WAHID
ASMAA RIAZ

2.  Definition:
Fibrous protein are the group of protein that are specifically
associated with the “rod” or “wire” shape.
They are usually inert structural or storage protein.
They are generally water insoluble proteins.
They are usually used to construct connective tissues,
tendons, bones and muscle fiber

3.  Examples:
1. Keratin
2. Collagen
3. Elastin

4.  History:
In the early 1950s the basic structure of the fibrous
proteins were determined.
It was found that long protein chains were composed
of strings of amino acid, could be folded up in a
systematic manner to generate a limited number of
structures that are

5. consistent with the X-ray data.
Most important of these structures are
alpha-helix, beta-sheets and the collagen
triple helix.

6.  Characteristics:
Following are the some major functional
characteristics of the fibrous proteins.
Biological function
Water Solubility
Amino Acid Composition
Secondary Structure
Tertiary structure
Examples

7. contd.,
Biological Functions:
Fibrous protein often have storage or structural roles such as
the collagen that is found in bone and cartilage.
Water Solubility:
Fibrous Proteins are insoluble in water.

8. Amino Acid Composition:
Fibrous protein often have repeated sequence of
amino acid.
Comparatively stronger intermolecular interactions
occur amongst the amino acid of the fibrous protein.

9. Secondary Structure:
Alpha-helixes and the beta-sheets.
Tertiary Structure:
Yes. The tertiary structure of fibrous
protein result in long fiber like structure.

10.  Examples:
Keratin in nails and hair
Collagen in bones and cartilage
Elastin

11. Collagen
By: Muhammad Mehdi
(16-Arid-2609)

12. Introduction
Collagen is recognized as a complex , interactive compilation of
protiens in dynamic equilibrium that can regulate the genes
expression of cells
It is most abundant protein in mammals . Accounts for 25-30%
of their protein content .
Many fibrous component of skin , bone , tendon and
cartilage.

13. When colagen heated in water , it gradually breaks down to
produce solube derived i.e . Gelatin or animals glue.
Denatures at a high temperature , remains stable at body
temperature
Collagen molecule is rigid and rod like structure that resists
stretching .
It influences cell shape , differentiation and other cellular
activities.

14. Basic structure of collagen:
Composed of three polypeptide alpha chains coiled around
each other to form triple helix configuration
Depending upon the type of collagen, the molecule may be
homometric (3 identical alpha chains)
Hetrometric ( 2 or 3 different alpha chains)

15. Conti…
Alpha chains that are left handed helices wrap around each
other to form right handed rope like triple helical Rod
Each alpha helix is 1.4nm in diameter and 300nm in
length
3 amino acid per turn (Gly-X-Y) repeat,,, frequently 30%
being X=proline & Y=hydroxyproline
Glycine occupies every third position in the repeating
amino acid sequence

17. Types of collagen:
19 types of collagen found Variation occur due to
1) Differences in the assembly of basic polypeptide chains
2) different length of the helix
3) Various interruption in the helix
4) Differences in the termination of the helical domain

19. Functions of Collagen Proteins
Collagen fibers support body tissues, plus collagen is a major
component of the extracellular matrix that supports cells.
Collagen give the skin its strength, waterproofing, and elasticity
. Loss of collagen is a cause of wrinkles.

20. CONTINUED
Connective tissue consists primarily of collagen
Collagen forms fibrils that provide the structure for fibrous
tissue, such as ligaments, tendons, and skin.
Collagen also is found in cartilage, bone, , the cornea of the eye,
intervertebral discs, muscles, and the gastrointestinal tract.
Collagen is used in cosmetic treatments and burn surgery.
Collagen is used to produce gelatin.

21. Synthesis Of Collagen Protein
First, a three-dimensional stranded structure is assembled, with
the amino acids glycine and proline as its principal components.
This is not yet collagen but its precursor, procollagen.
Procollagen is then modified by the addition of hydroxyl; groups
to the amino acids proline and lysine. This step is important for
later glycosylation and the formation of the triple helix structure of
collagen
These hydroxylation reactions are catalyzed by two different
enzymes: prolyl-4-hydroxylase and lysyl-hydroxylase.
Vitamin C also serves with them in inducing these reactions

22. Continued
• Transcription of mRNA
• Pre-pro-peptide formation
• Pre-pro-peptide to pro-
collagen
• Golgi apparatus modification
• Formation of tropocollagen
• Formation of the collagen
fibril
The
synthesis
of collagen
occurs
inside and
outside of
the cell.
Steps

24. Keratin Proteins
By: Faheen Riaz
(16-Arid-2596
)

25. Introduction
Keratin is one of a family of fibrous structural proteins
It is the key structural material making
up hair, horns, claws, hooves, and the outer layer of
human skin.
Keratin is extremely insoluble in water and organic solvents.

26. Occurance
Keratin filaments are abundant in keratinocytes in the cornified layer of
the epidermis
keratin filaments are present in epithelial cells in general.
the α-keratins are found in all vertebrates
the harder β-keratins are found only in the sauropsids, that is all living
reptiles and birds.
They are found in the nails, scales, and claws of reptiles, some reptile
shells (Testudines, such as tortoise, turtle, terrapin), and in the feathers,
beaks, and claws of birds.

27. Horns such as those of the impala are made
up of keratin covering a core of live bone.

28. Genes
The human genome encodes 54 functional keratin genes which
are located in two clusters on chromosomes 12 and 17.
The neutral-basic keratins are found on chromosome 12
(12q13.13).

29. Continued
 The acidic keratins are found on chromosome 17
(17q21.2).

33. Functions of Keratin Proteins
The Role Of Keratin. Keratin is a vital protein for the production of
human skin, hair, and nails. In fact, about 95% of the makeup of hair is
simply keratin
Keratin is also used in keratin treatments, which are designed to smooth
and shine hair. ... In a salon keratin treatment, keratins are mixed with
formaldehyde and applied to the hair with a flat iron and sealing the
protein into your hair.
. Keratin is also the protein that protects epithelial cells from damage or
stress

34. In The Skin
keratin has two main functions in the skin:
1. To hold skin cells together to
form a barrier
2. To form the outermost layer of our skin,
that protects us from the environment

35. Diseases
Diseases caused by mutations in the keratin genes include:
Epidermolysis bullosa simplex
Ichthyosis bullosa of Siemens
Epidermolytic hyperkeratosis
Steatocystoma multiplex
Keratosis pharyngis
Rhabdoid cell formation in Large cell lung carcinoma with rhabdoid
phenotype

36. Intermediate Filaments
Keratin filaments are intermediate filaments. Like all
intermediate filaments, keratin proteins form
filamentous polymers in a series of assembly steps
beginning with dimerization;
dimers assemble into tetramers and octamers and
eventually, if the current hypothesis holds, into unit-
length-filaments (ULF) capable of annealing end-to-
end into long filaments.

38. Elastin
A highly elastic protein in connective tissue
Allows many tissues in body to resume their
shape after stretching or contracting.
Elastin helps the skin to return to the original
position when it is poked or pinched.

40. Occurrence & its importance:
Elastin is found in skin & body tissues
It is a protein that helps to keep our skin flexible & tight.
It also keeps the skin smooth as it stretches to accommodate normal activities like
flexing muscles or opening & closing the mouth to talk or to eat.
Elastin is an imp load bearing tissue in the bodies of vertebrates & used in places
where mechanical energy is required to be stored.
In human Elastin is encoded by ELN gene.

41. Function & structure of elastin:
ELN gene codes for a protein that is one of two component of elastic
fibers
Encoded protein is rich in hydrophobic amino acids such as
glycine and proline which form mobile hydrophobic regions
bound by crosslinks between lysine residues.
Composed primarily of small non polar amino acids residues (G
, A , V).
ALSO rich in proline & lysine but little contains hydroxyproline &
hydroxylysine.
interchain cross-links form desmosine residues.