Peptide Secondsry Structure

Question 1

What are amino acids called when they joined in a peptide chain

Answer 1

Residues

Question 2

Why is there rotation around the bond in a peptide chain?

Answer 2

Because the partial double bonds keep the backbone rigid

Question 3

The secondary structure has hydrogen bonds formed between residues, where are the bonds

Answer 3

Between the carbonyl oxygen (double bonded oxygen) and the hydrogen linked to nitrogen (in the amine)

Question 4

What allows hydrogen bonds formed between O and H

Answer 4

The electro negativity of oxygen- pulls electrons towards it

The electro negativity of hydrogen+ pulls protons to it

They then form hydrogen links

Question 5

In the alpha helix , how many residues on average are in each turn?

Answer 5

3.6

Question 6

Why are the hydrogen links described as linking N+4?

Answer 6

Because then links are between every 4th amino acid residue, hence the 3.6 residues per turn

Question 7

Give an example of a protein with alpha helix structure that then allows binding to dna helix

Answer 7

Transcription factors. The particular side chains in the alpha helix allow gene turned on

Question 8

Which angle do side chains point in beta sheet?

Answer 8

180• alternatively

Question 9

Are beta sheets bonds between strands ?

Answer 9

Yes

Question 10

Antiparallel beta sheet has different angled bonds to parallel strands, explain

Answer 10

Antiparallel = straight aligned H-O bonds

Parallel= slanted bonds which are weaker