Proteins 2

  1. What can denature proteins?
    • Heat - breaks weak bonds
    • pH - affects hydrogen bonding and electrostatic interactions
    • Detergents and organic solvents - hydrophobic bonds
    • Chaotropic agents eg urea - form hydrogen bonds with amino acids and disrupt existing hydrogen bonding and hydrophobic interactions
  2. Can protein denaturation be reversed?
    Yes, as long as the 1y sequence (which dictates the protein's structure) is unaffected
  3. How many strands is collagen made up of?
  4. What amino acid occupies every third position in collagen?
    Glycine - it is the only amino acid small enough to fit into the tight centre
  5. Describe what happens in scurvy
    Scurvy is caused by a vitamin C deficiency.  Vitamin C is a co-enzyme for prohydroxylase.  Low levels of vitamin C means there is insufficient hydroxylation of proline which means there are fewer hydrogen bonds able to form and the collagen molecules become more unstable.
  6. What is brittle bone syndrome caused by?
    A mutation in the Gly codon meaning glycine is not present in every 3rd position in collagen.
  7. What happens to the structure of proteins in a prion disease?
    The structure of proteins change from their normal, globular form (alpha helix) to a non functional fibrous form (beta sheets).
  8. Why is it thought that the loss of chaperone protein function may contribute to prion diseases?
    Chaperone proteins are involved in changing proteins back from the fibrous form into the globular form.  Their loss of function would mean less proteins are converted back into the globular form which would allow the accumulation and aggregation of the fibrous form - which disrupts neurological function.
  9. Allosteric proteins have more than one subunit. When each of the subunits are in either:
    a) the tense form
    b) the relaxed form
    do they have a high or low affinity for ligand binding?
    • a) low affinity
    • b) high affinity
  10. How can the activity of allosteric proteins be regulated?
    • Allosteric regulators bind at other sites and they alter the affinity of the subunit for the ligand.
    • Positive allosteric regulators increase ligand affinity
    • Negative allosteric regulators inhibit ligand affinity
Card Set
Proteins 2
Module 2 - Week 1 - Proteins 2