You are required to make a solution of binding protein a (bpa) half saturated with its binding partner ligand a. the kd of ligand a for bpa is 1 x 10-5m and it has a molecular weight of 250. how much of ligand a needs to be added to a 2000 ml solution of bpa?

You are given the molarity of the solution which is 1x10-5 M. Since molarity is moles of solute over liters solution. You could determines the moles.

M=m/V
1x10-5 = m/(2 L)
m = 2x10-5 moles ligand A

We could determine the mass of ligand A by using the molar weight:

2x10-5 mol * 250 g/mol = 0.005 grams of ligand A

I hope I was able to answer your question. Have a good day.