For All Medical & Non Medical Students

1. Structure & Functional Relationship
of proteins
By
N.Santhosh Kumar
Asst.Professor
Department of Biochemistry
SIMS & RH

2. • Three dimensional structural conformation provides
& maintains the functional characteristics and dependent on
the primary structure.
• Any difference in the primary structure may produce a
protein, which cannot serve its function.

3. Structure Of Insulin
Intrachain
Inter chain
30
21
1
1
7
7
20
19
6 11

5. Metabolic functions of Insulin

6. Many genetic diseases are caused by minor changes in amino acid
sequence of proteins.
Ex: Sickle cell anemia and cystic fibrosis
HbA: “N”end -Val-His-Leu-Thr-Pro-Glu-Glu-Lys- C end
HbS: “N”end -Val-His-Leu-Thr-Pro-Val-Glu-Lys - C end
6
Non polar , nonionic hydrophobic a.a
Polar ,acidic, hydrophilic a.a
Sickle cell anemia
6

7. Enzymes
 In enzymatic catalysis: Binding of the enzyme to the substrate.
 Depends on the structural conformation of the active site of the
enzyme, is precisely oriented for substrate binding.
Specific amino
acid residues

8. • Active site possesses three dimensional structure
• Binding residues: Recognize & bind the correct substrate to
form ES complex
• Catalytic residues: Create a chemical environment that enhances
the reaction rate and Converts ES complex to E and P
• Change in the 1O, 2O, 3O & 4O structure may alter the 3 dimensional
shape of the active site of the enzyme & reduces its binding and
catalytic activity

10. Transport Proteins

11. Hemoglobin
• Conjugated proteins (Heme +globulin) found in RBCs.
• Carriers of O2 from the lungs to the tissues & carries CO2
tissue to the lungs.
• Normal value:14 to16 gm/dl (male); 13 to 15 gm/dl (female)

12. Globin
 Hb contain 4 polypeptide chains (2-α-chains - 141 a.a residue each
& 2β/2γ/2δ as per the type of Hb & have 146 a.a residues each.
 To each polypeptide chain one molecule of heme attached. therefore
Hb has 4 heme mole.

13. • Four globin polypeptide chains with four heme held together
-quaternary structure of Hb.
• Stabilized by H- bonds, salts bridges & vanderwal forces

14. Myoglobin
• Monomeric O2 binding hemoprotein.
• Found in skeletal muscle, cardiac
muscle, smooth muscle
• Single PP chain contains 152a.a’s
with heme moiety
• 17,500D MW (1Mb + 1O2 )
• Functions as a reservoir for O2

15. • Serves as O2 carrier that promotes
the transport of O2 to the rapidly
respiring muscle cells.
• Mb has higher affinity for O2 than
that of Hb
• Mb has a high O2 affinity while
bohr effect, cooperative effect &
2,3 BPG effect are absent

16. Collagen
• It represent primary source of structural strength for cells
(cytoskeleton) & tissues
• Skin derived its strength & flexibility from an intertwined
mesh of collagen & keratin fibers- bones & teeth
• Collagen forms a super helical cable where the 3 polypeptide
chains are wound around itself

17. • In collagen, every 3rd
residue is a glycine.
• The only amino acid that
can fit into the triple
stranded helix is glycine.
• Triple helix of collagen is
stabilized by the steric
repulsion of the rings of
OH-proline & also by the
H- bonds between them.

20. • Lens proteins –α, β & γ Crystallins – lens
transparent
• Lens proteins changes in their three
dimensional structure, becomes opaque
• In DM when B.Glu levels increased, lysine
residues of these proteins are glycated
• Leads to increased susceptibility for sulfhydryl
oxidation and consequent aggregation of
proteins –cataract

21. • Protein aggregates will produce
scattering of light, so that light is
not passed correctly to the retina.
• Aldose reductase reduces MS to
sugar alcohols. (Glu to D-
Sorbitol, Gal to D- Dulcitol)
• These polyols do not readily
cross cell membranes &
accumulate causing osmatic
swelling & consequent disruption
of cell architecure

22. You don’t always need a plan.
Sometimes you just need to
breathe, trust, let go and see
what happens.
don’t waste your time…
The End
Thank You