Protein structure (5)

Question 1

What is conformational change, what can it be driven by and why does it happen?

Answer 1

-proteins change their tertiary shape on binding a small ligand
-driven by e.g substrate binding or phosphorylation
-happens because 3D structure isn’t very stable

Question 2

Describe the protein binding site

Answer 2

-can be tight or weak
-usually very specific
-active site can be built from residues on very different positions on primary sequence

Question 3

How do ligands bind to the protein binding site?

Answer 3

Using non-covalent bonds

Question 4

What are the different types of post translational modifications of amino acids?

Answer 4

-phosphorylation
-glycosylation
-hydroxyproline
-carboxyglutamate

Question 5

Describe the post translational modifications of amino acids by phosphorylation

Answer 5

-hydroxyl groups of Ser, Thr + Tyr can be reversibly phosphorylated
-process often acts as a molecular switch in regulating cellular processes

Question 6

Describe the post translational modifications of amino acids by glycosylation

Answer 6

-many proteins found on cell surfaces or secreted acquire carbohydrate units on specific Asn residues
-increase hydrophilicity + ability to interact with other molecules
-can also link to Ser + Thr

Question 7

What do protein families consist of?

Answer 7

-a number of members
-each have closely related amino acid sequence + 3D structure
-have differing functions

Question 8

How do protein families arise?

Answer 8

Divergent evolution from a common ancestor

Question 9

What is the serine protease family?

Answer 9

-family of proteolytic enzymes including digestive enzymes + some involved in blood clotting
-each member cuts the polypeptide of their substrate molecule after a different residue