Question: A protein (R) is a trimer, which you suspect may exhibit cooperative binding. Each monomer contains a single binding site for the ligand, A. To investigate this you obtain the this data shown with [R] total=20uM. Make a hill plot of the data and determine the dissociation constant, Kd and the hill constant, nH. If present what type of cooperativity does R display with respect to A.

[A] total(mM) [A] bound (uM)

0.3 0.814

0.6 4.56

0.9 11.3

1.2 19.7

1.5 27.9

2 38.8

3 50.4

4 55.1

6 58.2

8 59.1

12 59.7