4 - Protein Structure

Question 1

Types of non-covalent bonds that form in protein structures?

Answer 1

Hydrophobic
Van deer Wal
H-bonds
Ionic bonds

Question 2

How does an A-helice form from a leucine zipper?

Answer 2

Leucine residue @ every 7th residue
Forms hydrophobic region running down one side of helix

Disulphides bonds form between two polypeptides

Question 3

Gibbs eq?

Answer 3

.

Question 4

Why is entropy +?

Answer 4

Unfolded
- h20 spheres around hydrophobic side chains [ordered so S-]

Hydrophobic interactions release h20 and disrupt spheres
[disorder so S+]

Question 5

Why is enthalpy -?

Answer 5

To break non-cov bonds energy in
So enthalpy is +

So to form them it will be -

So as protein folds

• S+ as disorders
• H- as bonds form

Question 6

Overall Gibbs?

Answer 6

H wins over S and Gibbs is -

So protein folding is spontaneous