Types of Post Translational Modifications

Question 1

Peptide cleavage

Answer 1

shortening of a peptide to ensure correct folding

Question 2

cysteine-cysteine disulphide bond formation

Answer 2

stabilises protein structure

Question 3

phosphorylation

Answer 3

often acts as a switch, turning a protein on or off (kinase is the enzyme who’s function is to add phosphates)

Question 4

Glycosylation

Answer 4

addition of glucose/sugars. increases stability and reduces flexability of proteins

Question 5

Hydroxylation

Answer 5

addition of a hydroxyl group. converts hydrophobic residues into hydrophilic residues
- needed to prevent connective tissue diseases and scurvy, often proline and lysine involved

Question 6

carboxylation

Answer 6

addition of a carboxyl group. mostly occurs in blood clotting proteins
- often glutamate involved