Question

Which set of binding data is likely to represent cooperative ligand binding to an oligomeric protein?

(a)

[Ligand] (mM)	Y
0.1	0.3
0.2	0.5
0.4	0.7
0.7	0.9

(b)

[Ligand] (mM)	Y
0.2	0.1
0.3	0.3
0.4	0.6
0.6	0.8

Short answer

The set (b) of binding data is likely to represent cooperative ligand binding to an oligomeric protein.

Step-by-step solution

Cooperative versus Noncooperative binding

In the case of cooperative binding, the graph of [Ligand] versus Y appears to be S-shaped, that is, sigmoidal. On the other hand, in the case of non-cooperative binding, the graph of [Ligand] versus Y appears to be logarithmic

Binding data set (a)

The [Ligand] versus Y graph for binding data set (a) is as follows:

As the graph suggests, the plot of [Ligand] versus Y appears to be logarithmic. Thus, the binding data set (a) represents non-cooperative ligand binding to the protein.

Binding data set (b)

The [Ligand] versus Y graph for binding data set (b) is as follows:

As the graph suggests, the plot of [Ligand] versus Y appears to be somewhat sigmoidal. Thus, the binding data set (b) represents cooperative ligand binding to the protein.

Hence, the data set (b) represents cooperative ligand binding to an oligomeric protein.