A simplified presentation of the complex and crucial process of protein folding which takes place after an amino acid chain is translated by ribosomes from mRNA.

1. PROTEIN
FOLDING
MARIAM SHAFIQUE
021

2. PROTIEN FOLDING
• A process in which a polypeptide folds
into a specific, stable, functional,
three-dimensional structure.
• Can only perform their various functions
when they are folded.
• Instructions for folding a protein are
encoded in the sequence.
• Failure to fold properly produces inactive
or toxic proteins that malfunction and
cause a number of diseases

3. AMINO ACIDS
• Monomers of proteins.
• Joined together by peptide bonds
• Amino acid sequence of a protein
determines its 3D structure.
• Amino acids in the chain interact
with each other to form a well-
defined, folded protein

4. Classification Of Amino Acids
• Based on the chemical properties.
• The side chain is going to dictate what group the
amino acid is in.
Proteins
Polar
(Hydrophilic)
Acidic
Basic
Neutral
Non-polar
(Hydrophobic)

6. Four levels of protein
structure

7. Primary structure- Assembly
• The order of amino acids in the chain which is
determined by DNA.

8. Secondary Structure-Folding
• Regions of regular folding due to hydrogen bonds
between amino acids that are close to each other
• The bonds are between atoms in the backbone of
the polypeptide chain.
• Its not about side chains; its about amine and
carboxylic group.
• Two different types of structure;
o Alpha helices
o Beta sheets

9. α-helix
• How does the protein stays in the lipid bilayer?
• The properties and sequences of amino acids keep
the receptor anchored in the cell membrane.
• The alpha helices gives the receptor rigidity in the
fluid lipid bilayer.

10. β-sheet
• The β-sheets form in two distinct ways.
o Parallel β-pleated sheets
o Anti parallel β-pleated sheets.
• It gives the protein tensile strength

11. α-helix Vs β-sheet

12. Tertiary Structure- Packing
• This takes the α-helixes and β-sheets and allows
them to fold into a three dimensional structure.
• Take on a globular structure once folded
• Have a hydrophobic core surrounded by a
hydrophilic outer layer
• Help create channels and binding sites for
enzymes.
• Interactions and bonding of the amino acid side
chains in the protein determines it.
• It has; hydrogen, ionic, disulfide bonds and
hydrophobic interactions.

14. Quaternary Structure-
Interaction
• Interaction of two or more polypeptide
chains of tertiary structure into a
single functional group.
• E.g. Hemoglobin or DNA polymerase.
• Dimer, trimer, tetramer
• Generally categorized as;
o Globular (hemoglobin, insulin,
enzymes etc.)
o Fibrous (collagen, keratin, silk etc.)
Globular
Fibrous

15. Chaperones- Helper
• Protein folding takes place in a highly crowded,
complex, molecular environment within the cell
• Requires the assistance of molecular chaperones,
in order to avoid aggregation or misfolding.
• Protein folding is influenced by several external
factors.
• Chaperones help proteins to fold and remain folded
under extreme temperatures.
• They have an environment that is ideal for protein
folding

17. THANK YOU
FOR YOUR
ATTENTION!