2.1 Protein Structure

Question 1

Primary Structure

Answer 1

Sequence of 50+ amino acids in polypeptide chain.

Question 2

Bonds in primary structure

Answer 2

peptide bonds - planar

Question 3

Bonds in secondary structure

Answer 3

Electrostatic force between hydrogen

Hydrogen bonds between C-O and NH on alpha helices and beta sheets

Question 4

Bonds in tertiary and quaternary structure

Answer 4

Hydrophobic and Van der walls - induce temporary dipoles

Ionic bonds - between AA R-groups

Question 5

Secondary structure

Answer 5

pattern of hydrogen bonds in the peptide backbone - alpha-helix and beta-sheets

Question 6

Tertiary structure

Answer 6

final 3D shape, can contain tertiary domains

Question 7

Tertiary domains

Answer 7

Smallest stable unit of tertiary structure, if removed the protein structure stays the same.
Domains can be swapped between proteins - domain shuffling.

Question 8

Quaternary structure

Answer 8

Multiple tertiary structures arranged together in a multi-subunit. Can change shape in response to activators and inhibitors.

Question 9

Collagen structure

Answer 9

three fibres in a triple-gamma-helix held by h-bonds.

Gly-X-Y

• Glycine is smallest AA so sits inside helix
• X is often proline, lysine or hydroxylyproline
• Y is often proline or hydroxlyproline

Question 10

What is a prion

Answer 10

Proteins within neutral tissue that can become infectious depending on their folding.

Two types - infectious and normal

Question 11

Infectious prions

Answer 11

Tighter structure with more beta sheets. form fibril-like polymers that can break off and seed new fibrils that can clump to form plaques.

Question 12

Normal prions

Answer 12

Looser structure