Proteins 2

Question 1

Describe the structure of alpha helix

Answer 1

Right handed helix
3.6 residues per turn
Good H bonding

Question 2

How are secondary structures held together?

Answer 2

By hydrogen bonding in the backbone

Question 3

What bonding occurs in alpha helices ?

Answer 3

n to n+4
The hydrogen bond forms between:
The carbonyl oxygen in the AA at position n
And the amide hydrogen of the AA at position n+4

Question 4

Name some examples of helix formers

Answer 4

Glutamate
Glutamine
Alanine

Question 5

Name a helix destabiliser

Answer 5

Tryrosine

Question 6

Name a helix breaker

Answer 6

Proline
Barely ever found in helix as it cannot rotate or participate in H bonding

Question 7

What holds together anti parallel beta sheets ?

Answer 7

Hydrogen bonding

Question 8

What are anti parallel beta sheets ?

Answer 8

Then one strand is running in the N to C direction and the other strand is running in the C to N direction

Question 9

What is an example of an anti-parallel beta sheet ?

Answer 9

Silk
It has long stretches of (Gly Ala)n
Will not stretch in the longitudinal direction

Question 10

What is a parallel beta sheet ?

Answer 10

Both chain run N to C direction

Question 11

Name some structural motifs

Answer 11

1. All alpha - hameoglobin
2. A beta - immunoglobulin
3. Alpha/beta motifs - Triose phosphate isomerase
   They are recurring patterns of secondary structures in proteins