Chapter 4

Question 1

conformation of a poly-chain: each alpha carbon is held

Answer 1

within the main chain through single bonds where there is freedom of rotation

Question 2

the single bonds in conformation are defined as (2)

Answer 2

phy and psi

Question 3

each peptide bond has both a

Answer 3

hydrogen bond donor and a hydrogen bond acceptor

Question 4

in alpha helix - each C=O bond forms

Answer 4

a hydrogen bond with the amide hydrogen of residue n+4

Question 5

alpha helix is a what with what

Answer 5

dipole- with +N, -C termini

Question 6

draw alpha helix structure

Answer 6

H H R H H R H
| \/ | \/ |
N——-C–C—N——-C–C—N
|| ||
O O

Question 7

which amino groups are not regularly found in alpha helicies

Answer 7

• proline-is known as a helix breaker and is not normally found in alpha helicies
• glycine - because it is flexible, not usually found in alpha

Question 8

stretches of similarly charged residues are

Answer 8

not observed as they will destabilize the helix due to electrostatic replusion

Question 9

a small electrical dipole exists in each peptide bond causing

Answer 9

the N terminus of the helix and the C terminus carry partial positive charges

Question 10

postitioning of hydrophobic and hydrophilic residues with the primary structure can

Answer 10

generate an amphypathic helix with hydrophobic and hydrophilic faces