Question

LLI (nM) 92 The data at right describe the binding of a ligand to a protein: 0.1 0.07 s [L] is the concentration of free ligand. e is the fraction of sites on the protein that are occupied by the ligand. (Note that some textbooks use terms like v or Y, instead of 6, to denote fractional saturation) 0.4 0.23 0.36 Answer parts (a) and (b) below. 0.55 1.2 (a) Which of the following graphs could be used to estimate Kd for the data? 0.68 1.5 0.78 10 0.83 0.84 09 6.4 0.7 06 O A and D 0.5 O A and E 0.4 O B and D 0.3 O B and E 0.2 O C and D 0.1 continued 00 0 0.5 1.0 1.5 20 25 3.0 35 4.0 4 5 5.0 55 6.0 6.5 7.0 below. air lata

Answer 1

From the above shown binding curves,

The curve that could be used to determine Kd would be,

(b)

From the graph (b), the Kd value calculated would be,

Kd = 1/0.3 = 3.33 nM