Question

1.00 0.75- fractional saturation 0.50 0.25- 0.00 0 T 7 1 2 3 4 5 6 [ligand] mM Above are shown ligand binding curves for protein DOT (black circles) and protein TRG (black triangles). Choose the correct option that best describes the data. TRG's Kd for ligand is 0.6 mm DOT binds to ligand with a 5 fold higher affinity than TRG DOT binds ligand less efficiently that TRG, the DOT affinity is 5-fold lower that TRG TRG and DOT both have the same Kd value for the ligand

Answer 1

Binding affinity is typically reported as equilibrium dissociation constant (K_D). The smaller the K_Dvalue, the greater the binding affinity of the ligand for its target.

P + L <===> PL

K_D = [P] [L] / [PL]

( P : protein ; L : ligand )

From cuves it is clear clear that : K_D(TRG) > K_D (DOT)

Thus affinity for DOT is greater than TRG.

fraction saturation , θ = [PL] / [P]+ [PL]

OR θ =   [L] / [L]+K_D

_{1.00 0.75- fractional saturation 0.50 0.25- 0.00 0 T 7 1 2 3 4 5 6 [ligand] mM Above are shown ligand binding curves for protein DOT (black circles) and protein TRG (black triangles). Choose the correct option that best describes the data. TRG's Kd for ligand is 0.6 mm DOT binds to ligand with a 5 fold higher affinity than TRG DOT binds ligand less efficiently that TRG, the DOT affinity is 5-fold lower that TRG TRG and DOT both have the same Kd value for the ligand}