Collagen & Elastin with disorders

1. SNEHITA PRASAD
LECTURER
Department of biochemistry
Narsinhbhai patel dental college & hospital

2. CONNECTIVE TISSUE
 Connective tissue serves a connecting function.
 It supports and binds other tissues.
 Connective tissue is a system of insoluble protein fibers embedded in a matrix called the ground
substance.
 Connective tissue is widely distributed in the body, the tendons, ligaments, cartilage and matrix of bone.
Function
Strength
Support
shape

3. Basic components
Collagen Elastin proteoglycans Glycoproteins
CONNECTIVE TISSUE

9. TYPES OF COLLAGEN

10.  The collagen is synthesized by fibroblasts intracellularly, as a large precursor, called procollagen.
SYNTHESIS OF COLLAGEN

11. STEPS OF BIO-SYNTHESIS OF COLLAGEN
Hydroxylation of proline and lysine
Glycosylation of procollagen
Extracellular maturation of collagen
Formation of Triple helix
Quarter-staggered arrangement

12. MATURATION OF COLLAGEN
Inside the
fibroblasts;
polypeptides are
synthesized,
proline and lysine
residues are
hydroxylated
Glycosylation of
lysine takes place.
procollagen
molecules are
secreted. Outside
the cell,
procollagen is
cleaved by
fibroblast-specific
Peptidases
Tropocollagen
molecules are
assembled
into collagen.
Finally, covalent
cross links are
formed.
GLYCOSYLATION
The hydroxylated polypeptides are next
glycosylated.
The common carbohydrate residues added are
galactose and glucose, which are added
sequentially by galactosyl and glucosyl
transferases.
The glycosylation occurs only on the hydroxy
lysine residues.
HYDROXYLATION
The hydroxylation of proline and lysine residues of collagen is a
post-translational modification taking place intracellularly. Prolyl
hydroxylase and lysyl hydroxylase are both dioxygenases using
molecular oxygen.
The enzyme also contains ferrous iron at its active site an requires a
reducing agent like ascorbic acid to preserve the iron in the reduced ferrous
state. So, vitamin C deficiency leads to poor hydroxylation. It is the major
biochemical defect in scurvy

13. CROSS-LINK OF COLLAGEN FIBERS
The collagen fibers are strengthened by covalent cross-links between lysine and hydroxy
lysine residues. The cross-links are formed by lysyl oxidase which converts these amino
acids into aldehydes. These are called aldol cross links.
In copper deficiency, reduced cross-linking
of collagen
QUARTER-STAGGERED ARRANGEMENT
The tropocollagen molecules are arranged in
a'quarter staggered array' to form the collagen
fibers
The structure repeats after each row . Thus, the
collagen fiber has triple stranded, quarter
staggered arrangement.
This arrangement helps in mineralization.
TRIPLE-STRANDED HELIX
The collagen is a rod like structure. Each of the 3polypeptide chains is
held in a helical conformation by winding around each other.
The three strands are hydrogen bonded to each other. Glycine, because of
its small size can fit into the crowded interior of the collagen triple helix

16. ELASTIN

19. DISORDER
OF
CONNECTIVE TISSUE

21. SCURVY EHLERS-DANOLS
SYNDROME
OSTEOGENESIS
IMFECTA