A heterotrimeric protein is composed of three subunits that have similar structures. Each subunit is able to bind to the same ligand molecule. Binding of the ligand to one subunit has no influence on the affinity of the ligand for the other subunits.

Which of the following binding curves is/are likely to represent this type of protein-ligand interaction?

Shown below is a binding curve for a drug binding to a single binding site on a target protein.

From this curve estimate the fraction of protein molecules that will be bound to the drug when the concentration of the drug added to the solution is 8 nM.

Your answer should be given as a number, e.g., 0.5, not 50% (do not type any additional characters)

Which of the following statements are correct regarding the structures of myoglobin and haemoglobin and their abilities to bind oxygen?

In the course of their investigations into cancer cell growth, a team of pharmaceutical researchers has discovered a critical oncoprotein (a protein that promotes cancer cell growth).

Now they have developed a new drug that binds to a single site on the oncoprotein with an equilibrium dissociation constant (K_d) of 5 nM.

What concentration of the drug would they need to mix with the oncoprotein so that 99% of the oncoprotein molecules will be bound to the drug?

Three different mutant forms of myoglobin bind to oxygen with different affinities.

Their rank order of oxygen affinity is (from strongest to weakest):

Mutant Y > Mutant Z > Mutant X

The oxygen binding curves for these mutants are shown below.

Which curve corresponds to which mutant?

A protein binds to a single small molecule ligand. When the protein (50 pM) is mixed with the ligand (6 nM) and the solution is allowed to reach equilibrium, the proportion of protein molecules bound to the ligand is 10%.

From this single data point, estimate the equilibrium dissociation constant (K_d) for this interaction.

Type the answer as a number in units of nM but do not type the units or any other additional characters (e.g., type 10 rather than 10 nM).

A protein binds to a small molecule ligand with an equilibrium dissociation constant (K_d) of 0.5 μM.

In a sample containing the protein (10 pM) and the small molecule ligand (50 μM), what proportion of the protein molecules will be bound to the small molecule ligand at equilibrium?

Shown below is a binding curve for a ligand binding to a single binding site on a protein.

From this curve estimate the equilibrium dissociation constant (K_d) for this protein-ligand interaction.

A pharmaceutical researcher has determined that a drug binds to its target protein with a K_d value of 0.2 nM under physiological conditions. Considering that the target protein is present at a concentration of 1 pM or less, what concentration of the drug needs to be present in the vicinity of the target protein in order for the target protein to be approximately 99% saturated with the drug?

A pharmaceutical researcher has determined that a drug binds to its target protein with a K_d value of 0.5 nM under physiological conditions. Considering that the target protein is present at a concentration of 1 pM or less, what concentration of the drug needs to be present in the vicinity of the target protein in order for the target protein to be approximately 99% saturated with the drug?