B2.045 Prework 2 Cooperativity and Allostery

Question 1

what is the difference between allosteric and cooperative binding?

Answer 1

cooperative- same binding site, same ligand

allosteric- different binding site, different ligand

Question 2

how is allostery seen on an enzyme curve?

Answer 2

shift in Kd

Question 3

what are two types of allostery?

Answer 3

inhibitory allostery- initial substrate diminishes binding of second substrate
enhancing allostery- initial substrate enhances binding of second substrate

Question 4

why does nature need allostery?

Answer 4

regulation
regulation
regulation

Question 5

what are two examples of cooperativity?

Answer 5

homo-oligomers- binding site is repeated on each subunit

single polypeptide chain with identical binding sites

Question 6

how can you visualize cooperativity on an enzyme curve?

Answer 6

steeper sigmoidal curve; midpoint is weighted average of a site with low affinity and a site with high affinity

Question 7

what is the hallmark of negative cooperativity?

Answer 7

never reaches 100% bound

Question 8

how is positive cooperativity used in nature?

Answer 8

response range to ligand change narrows, aka once a little binds, a lot more can bind
similar to an on/off

Question 9

how is negative cooperativity used in nature?

Answer 9

changes at higher ligand concentrations do not affect protein function
constant protein function across a wide range of ligand concentrations

Question 10

what are some possible advantages of allosteric drugs?

Answer 10

more subtle effects, potential to ramp up function or slow it rather than on/off
expands the number of search targets